can't answer the second question but as far as the first, i believe it is either a percentage or a number derived from salvage price and/or what they think they can get at auction for it. it's been a while but i don't remember what it was. in my experiences, if the car was worth 5k and they wanted, say, $1k to buy back plus maybe a $1k deductible was, they'd simply give me the car back and a check for $3k (the value minus the buy back price minus deductible). those are just example numbers.