I found a used 1990 USA Fender Strat for sale at 400$. It has some rust on the frets and pickups. I also want to be sure that this is a genuine USA strat, so I wanted to know how I would check the serial # (I have it, I just want to know what serial #'s USA strats would have).

Should I buy it, and if I do, is there a way to get rid of the rust?
Ah, thanks, that helps a lot, thank you. What is the difference between "5 digits and 5 5 digits" (1990 vs 1989)? Also, I read something about "swimming pool route" that differentiated the 89 strat vs the 90?