You have asked several questions, so let's see if I can answer all in a brief format.
1. Olam Habah.
The crux of the question for olam habah is how you interpret the term.
If, by it, you mean another world, or some sort of life beyond the grave, I would say that most Reform Jewish thinkers would answer "no". This goes back to the ideological (and theological) position taken rejecting resurrection as a tenet of Judaism in the period of Classical Reform. I am not able to cite any studies showing general belief today, but the Reform rabbinate seems not to be unified in their approach to this question, so perhaps it is in flux.
On the other hand, if you mean by olam habah 'the world that is coming'; in other words, the improvement of this world, then I would say that most of the Reform thinkers would agree that this describes hopes for a messianic age (a time of peace for all, with no hunger, no poverty, and no oppression), and there would be general agreement that such an olam habah would be a possibility, and certainly something we should aspire to and work towards.
2. Living up to what is expected of you.
The Reform movement historically has emphasized the ethical and moral aspects of Judaism, especially as set forth in the Prophetic writings, so this question is in keeping with that approach. A fairly straightforward measure of this would be to conduct a self examination, and determine if you are acting justly and with kindness, supporting those around you in need, and making the world a better place. In this way of thinking, the instruction of Torah is the guide and the baseline, setting forth the goals; the details of how you are to do it are left to you. In this way of thinking, you are doing what God expects of you (if you believe in the divine origin of the Torah) and what you should expect of yourself as a human being, when you act in accordance with these principles and values. As a side note, this is the focus of the month of Elul and the Ten Days of Awe - the period leading up to Yom Kippur (the Day of Atonement), when we engage in introspection and examine our deeds in the past year.
3. God and God's Nature
I think that the jury is out on this one. Again, historically, at least some of the Reform movement's formative thinkers were uncomfortable with the idea of a personal God, and made some changes to the liturgy to remove that language, but as time has passed, that view is less clearly universal, and may be shifting (as I perceive to be the case in Reconstructionism). I do see many of the 'Jews in the pews' praying quite personally when they encounter a crisis; I am unsure what they think when things are going well for them. There has been movement in the Reform ranks towards more traditional ritual practices; perhaps this is also reflective of the view of God.
As for God's nature; I don't think there is a singular answer. Not for Reform, and probably not for Judaism as a whole. Perhaps the most commonly used analogy is God as a parent, however, God is depicted in the Tanakh (Hebrew scriptures) in multiple ways, and in Jewish thought the concept of God has changed and morphed over time. Even within the Tanakh, God is seen in many ways: angry, jealous, kind, loving, and a warrior, to note just a few. There is no single presentation, and no agreement on the nature of God.
In answering your several sincere questions, it is possible to take several different approaches. My usual approach is from my most personal inner self.
I am very much a believer in all of the areas asked. My answer very simply is, "Yes." Yes, I believe that there is an Olam Habah--the Next World. Yes, I believe that G-d approaches and judges us in terms of Torah and mitzvot. Yes, there is a G-d in a universal and personal sense. And, yes, G-d has a nature, but it is beyond our understanding.
Now, how do I or for that matter anyone else come to my decisions in any of these areas? It is a combination of nature and nurture. I have certain innate traits and I have been raised in a certain way.
When I am asked a question, I believe that I am asked because I am an exponent of Jewish Faith. I am an important cog in a very large mechanism. I have been raised and nurtured as a Jew and have been exposed to the greatest Jewish believers, scholars and practicianers of Judaism. Most important of which is my mother, of blessed memory.
I do not believe that one should turn to a rabbi for their personal view only, but rather for their learned response that reflects the heritage and tradition of a people. I believe that too many rabbis are at odds with their own faith and reflect in their answers positions which are in no way part of the heritage of Israel. This is sad and often helps to impoverish our people, who are in sincere quest for real answers.
I suggest looking into the traditional Jewish prayer book--Siddur. It addresses in a most straight forward way that questions that you have asked. My favorite siddur is the most famous edition of The Authorized Daily Prayer Book with commentary by Rabbi Joseph H. Hertz. This is not easy to find, but should still be available in a used book store, online or in a good Jewish library.
My favorite current Siddur is the Koren Sacks Siddur. The text and commentary are superb.
In summary, according to the Jewish Faith; yes, there is an Olam Habba. Yes, the Torah and Mitzvot are the measure by which G-d decides (with a very heavy dose of love and forgiveness. Yes, there is a G-d who is universal and personal. G-d's nature is impossible to comprehend and to define, but is in the end loving.
Is there Olam Haba? The Oral tradition of Judaism postulates the existence of a world to come – ‘Olam Haba’. Mishnah Sanhedrin chapter 10 states that all Jews are presumed to have a share in the world to come, then lists acts or patterns of behavior which can lead one to lose his/her share in the world to come if s/he were to die unrepentant from those acts, then lists examples of Biblical characters who have no share in the world to come. From the inclusion of Balaam, a non-Jew, on that list, Talmud Sanhedrin 105a derives that Balaam had no share, but other non-Jews – namely righteous gentiles (chasidei ‘umot ha’olam = those who fulfill the seven universal commandments God gave to Noah and his descendants after the flood) - do have a share in the world to come. (See also Mishnah Avot 4:1 and Mishnah Peah 1:1.)
Regarding the nature of this world to come and how it relates to this world, Mishnah Avot 4:16-17 states:
Rabbi Jacob says: This world is like an antechamber before the world to come. Prepare yourself in the antechamber so that you will be able to enter the banquet hall. He used to say: One hour spent in repentance and good deeds in this world is better than the whole life of the world to come; yet one hour of satisfaction in the world to come is better than a whole life of this world.
In his long introduction to his commentary on Mishnah Sanhedrin chapter 10, Maimonides analyzes how best to interpret what the “world to come” is. He concludes that “’olam haba’” is a spiritual realm experienced by the souls of humans after their death, dependent upon the extent of knowledge and consciousness of God that they were able to develop during their lifetimes. The broad description of that realm and its implications which follows is heavily influenced by the writings of Rabbi Aryeh Kaplan (which were heavily influenced by the mystical tradition of Kabbalah) in a collection of essays entitled, If You Were God. When the soul is separated from the body at death, it is freed from the restrictions which physical existence placed on it. In order to exist as human beings, we must be shielded from direct revelation of God’s overwhelming presence. Once we die, our souls are able to bask directly in the presence of God’s Glory (Kavod). When the soul is basking in the presence of God, the soul knows and understands everything about his or her life on earth, and everything about the purpose of life. To the extent that the soul fulfilled its purpose in life, it enjoys basking in God’s glory and experiences eternal joy – the joy which R. Jacob described as being better than all of this world. However, in the world to come, unpleasant memories cannot be blocked. The soul also knows how many opportunities were lost, frittered away on the vain and meaningless. The soul knows the pain of all those whom s/he hurt in life, for “olam haba” is “olam ha’emet” – the world of truth - where the truth about one’s life on earth becomes clear, often painfully clear. One whose life has been spent working at counterpurposes to the purpose for which God created him/her is filled with shame in the presence of God. Shame is compared in Bible and Talmud to a fire burning from within. When one hears images of the wicked burning in the hereafter, Rabbi Kaplan recommends that we understand that as the soul being tormented by its own shame. Most people live lives which are a mixed bag of good and bad. Jewish tradition holds that for such people, the soul only suffers from the shame for at most a year. After that, the soul learns to live with the shame while experiencing the joy accrued from the good s/he accomplished on earth. Those souls who have no good deeds whatsoever to commend them experience only endless shame. In this way, one hour of repentance and good deeds in this world is better than all of the world to come (where good deeds and repentance are no longer possible).
How do I measure whether I'm living up to what God/I expect of me?
Ultimately, only God knows for sure whether one is living up to what God expects of that person, and we will only know for sure when our souls are in God’s presence in the world to come. However, God gave us Torah and its mitzvot in order to guide us in the proper direction.
And now, Israel, what does the Lord your God ask of you, but to fear the Lord your God, to walk in all of His ways and to love Him, and to serve the Lord your God with all of your heart and all of your soul. (Deuteronomy 10:12)
He has told you, man, what is good and what the Lord requires of you: doing justice and loving mercy, and walking humbly with your God. (Micah 6:8)
When we sincerely and humbly walk in God’s ways – Halakhah – the path of life defined by Torah, seeking to do justice while loving mercy, with the full commitment of heart and soul, we are most likely living up to what God expects of us.
Is there a God/personal God in the traditional sense and if so what is his/her nature?
“No human can see God and live.” (Exodus 33:20) We cannot fathom God’s nature. We can only extrapolate from our experience of what God has given to us: the universe God created and the Torah God revealed to us. Judaism postulates that God is the source of all being, consciousness and wisdom, that God created the universe with wisdom for a purpose which only God fully understands. God created within humans a Godly spark (divine image). God is personal in the traditional sense in that God cares about each individual human being and how that human being uses the Godly power implanted within him/her. In order that humans have the freedom to choose whether or not to serve God, God has hidden His presence in this world so that humans have the capability of denying God’s existence or any divine purpose in the existence of the universe, as well as the capability to find and connect with God, to bring God’s presence into this world and fulfill the divine purpose of creation by walking in God’s ways to establish justice and righteousness.
See I have set before you today life and good and death and evil. As I command you this day to love the Lord your God, to walk in His ways, and to keep His commandments, His statutes, and His judgments, then you will live and prosper, and the Lord your God will bless you in the land which you are entering to inherit. But if your heart turns and you do not obey …. Life and Death I have set before you, blessing and curse. Choose life in order that you and your offspring will live. To love the Lord your God, to hear His voice and to cleave to Him, for He (or His voice) is your life and the length of your days …. (Deuternomy 30:16-20)
The choice is ours to make. The consequences will only be known for sure in the world to come.