I haven't talked this much philosophy in...ever. I've never had people intellectual enough to discuss it with, it's quite refreshing.
Well, assuming that all existence and aspects of it are conscious and sentient to at least some degree, it's certain that we were grown from this earth for a purpose. As for what that is, I'm gonna go with you, it just varies from person to person. Personally, I'm still unsure what mine is, but that doesn't bother me. I'm here, I might as well enjoy the stay, I'm sure I'll figure out my purpose at some point in my life.
That sounds extremely depressing O_O I would hate to relive my life over and over in a dream, because you'd constantly be reminded of mistakes and what you could have done differently. I prefer the idea of reincarnation (unless I was reincarnated in a post-apocalyptic world, that'd suck) myself, although I don't believe it.
I'd say our higher consciousnesses (our souls, if you will) will continue to exist in some form while our bodies rejoin the earth. We are all sprung from the same singularity, but our awareness and sentience is the highest of any creature on this planet, so I doubt it would just fade away. Perhaps it joins with the consciousness of the earth or universe *shrugs*