Repos are a pretty complex issue. I just recently dealt with one myself.
It is the biggest problem I have as far as my CRs.
It will stay on your credit (from the OC) for 7 years from the date of resale. (that is when the SOL clock starts)
As far as how much you owe, it depends. On what state you're in, how much you owed on the car and how much it sold for, etc.
It also makes a difference on how it is repo'd. It has to be sold in a commercially reasonable manner or there
should be no deficiency owed.
I say should......because I just got my a$$ sued and my car was not sold in a commercially reasonable manner.
Like I said, it's a bit complicated. I just need a little more info and maybe I can help answer your questions better.