I believe in reincarnation. I just don't think anyone has a true grasp on what it really is. We each have bits and pieces of knowledge, but no one can see the whole picture. I think the OP has some ideas that are probably correct, but so do some of the other posters. Like Curt and some of the rest, I believe Karma is just Karma. It's not good or bad. I don't believe life, or the afterlife is geared toward reward or punishment. That's why I don't believe in Heaven or Hell. Heaven is supposed to be reward for a life well lived, while Hell is punishment for a life badly lived. I don't believe that. I think the Divine is much bigger than that. Reward and punishment is a purely human concept. It was developed by small thinkers to control other small thinkers. The Universe, and the Divine go far beyond anything we could imagine.
Here is what I have come up with so far...
Everything has a "soul", a spirit, energy force, whatever one wishes to call it. It is our sentient essence that lives on beyond this life. Each time that essence is manifested in a "life" form, it's for the purpose of learning a lesson or lessons that life has to offer. The knowledge is not carried from one life to the next, but is gathered by the essence to make it whole. No one can possibly learn all they need to know in one lifetime, but each life has specific knowledge in it that the soul, or essence retains.
I do not believe reincarnation is a progressive process, like moving up a ladder, with each life creating a slightly better person than the last. I believe it's like putting together a puzzle. Each piece is a life lived. Each piece completed moves the essence toward fulfillment, toward its wholeness. People we may be repulsed by in this life, we may have been in a past life, or will be in the future. People like Stalin, Hitler, and Hussein may have simply been pieces in the puzzle of their souls. One can not fully understand "evil" without being evil. One can not fully understand "good", without being good. In between, there is a massive amount of "ordinary". most of us fall into that category. It's all for the purpose of learning. It's not good or bad, right or wrong. It's just learning what we need to learn in the manner that our individual essence, or soul, needs to learn it. Once our essence rejoins the Universal energy, we all become part of the same energy flow again.
I also believe that we don't necessarily reincarnate back to this planet, or plane. If that were so, where would everyone/thing go when this planet dies? The earth is around 4.5 billion years old. Like all other life, it will die someday. Our Sun will die too. Nothing lives forever. In all of the Universes, I can't believe this little planet is the only one with life on it. To be practical, I believe the human race will go extinct long before the planet dies. All species a born, live for a time, then die off. So will we. If our souls are eternal, then they go someplace. If they reincarnate, they will have to find a new home when this one is no longer inhabitable. It stands to reason that we already go to other planes, other planets, for the lessons our souls need or desire.
Just my penny's worth. : )