Well, it's an interesting topic, that's for sure.
I've died and been brought back. But technically, I wasn't totally brain dead or anything. Saw the tunnel vision thing, all light pinned out. I can't say I saw any pearly gates, but I can say it was a strange experience. From what I did experience, I would 100% say we have a body of energy which is our consciousness, or, soul. My consciousness was still quite active, although my perceptions of time/space were........skewed, don't know a better word. But then again, that might have just been something in my brain experiencing a comatose state. Dunno. I can say though that some weird shit happened, and I wouldn't know how to begin to describe it. Certainly I'm not the religious sort though.
What is a soul? I have absolutely no idea what it is, nor do I claim to understand it's purpose, or true nature, but I still believe in it.
What happens to a soul once a person dies? Well, I think the energy continues, and perhaps changes form.
If you believe in afterlife, describe it: I don't believe in a heaven or hell in the biblical, or religious sense. I think that we move on if we are at peace when we die. I think punishment for guilty feelings and wrong doings are inflicted upon ourselves by our own higher consciousness. I couldn't be more specific without getting heavily into psychic phenomenon and such, which most people are very skeptical about.
If you believe in reincarnation, describe its process: I think the law of conservation in thermodynamics sort of sums it up.