CNS, this is a very complex topic and will be addressed admittedly extremely inadequately, as I am kinda in a hurry, but I will try to paint an overall picture.
First and foremost, We are not bodies that posses souls, we are souls that posses bodies. This is a very subtle, but important distinction.
Secondly, everything is vibration. Conciousness is a reflection of vibration. Here is an example of how someone with a reincarnationist perspective might view some of the scenario's mentioned.
Lets look at dohminator's first scenario. You have someone who is obviously bitter and uncaring but gets changed in an instant because of an accident. Dohminator points out how he hasn't "paid for any of his sins." Yet when you look at it from a reincarnationist perspective, maybe he had. Being mean and uncaring produce thier own negitive vibrations anyway and people who are that way are usually not very happy, and often times miserable. Maybe that was payment for his sins. Even still, he will have to face in one way or another the negative energy which he put out in to the universe, whether this is an astral realm that resembles the catholic purgatory, or an earthly incarnation. Maybe the accident was an intersession of God to jolt him on the right path. For his Love and Grace are VERY real. Or maybe the accident was a result of his past karma which had set him up for a spectacular change. Either way, karmic "jolts" like this and complete changes in conciousness, as I stated are usually set up by past incarnations. Summer changes from fall to winter, even supernovas take time before they explode. In God's Universe changes take time and buildup, hence dramatic events like these have been "in the works," so to speak, for a while.
When dohminator says "In effect this person is now to seperate people." He is wrong. Same body, same soul, different states of conciousness. You could argue because my conciousness is different than it was when I was 10, that I am "two seperate people." But in reality is the fluid and ever-moving state of my conciousness.
Next you have the "very nice lady has an industrial accident that disables her ability to control her impulses. She now has sex like a fiend, is mean and roudy and hates on people." This causes her to move away from religion. This scenario has past life karma written all over it. Perhaps in several previous lives she repressed her sexual impulses drastically, perhaps she was so reserved and wound so tight that it knawed on her soul, causing her feelings of guilt and self contempt. Now her self contempt is being projected by being mean and rowdy and "hating on people." Thus, they do not like her back, and condemn her in the very way she condemned(s) herself. She must face and overcome her karma. However, she will have to deal with her promiscuity and mean and rowdyness in one way or another. We must meet all our challenges that occur due to karma. For example, a person who committs suicide (which is horrible, horrible, karma) will incarnate again and face that very same level of suffering, until he can overcome it.
Every action in this universe has a reaction. That is why raising our own vibration through prayer, meditation, chanting, devotion, etc. is important. For me it is based on results. When I meditate and pray regularly, I am more kind, loving, harmonious, patient, and peaceful. Qualities that burn away negative karmic vibrations, although, there is no way of getting rid of some things, other than facing them and conquering them.
This was admittedly rushed and incomplete, but I wanted to get you an answer before I chill out this weekend. Here are some things that might interest you CNS:
This movie talks about things that Indian yogi's have known for millenia, it is a great film.
http://www.whatthebleep.com/crystals/
