hashkafah philosophy - How does Judaism prove the existence of the life of the world to come?

I have three questions:

• What is the basis for the Jewish belief in the World to Come?


• What human traits does Judaism consider reflect the possession of an eternal soul?


• What purpose(s) is/are served by the afterlife and the World to Come that cannot be served by this world in its present condition?

Answer

Here is a good place to start: http://www.jewswithquestions.com/index.php?/topic/660-source-for-reward-and-punishment-in-the-next-world/ I asked Rabbi Shapiro of Basewater what is the source in scripture or otherwise for the world to come.