Obviously your mechanic will check it, but when they say there's new brakes, does that mean just brake pads, or pads & rotors? Like osso pointed out, it could be the rotors are bad.
The accident thing probably isn't a big deal. A lot of cars that old are going to have been in some accident. And carfax doesn't always have them listed. There has to be a police report for it to show up there.
And don't be afraid to negotiate on the price. Shoot to buy the car for $4500-5000. People who sell cars leave room to haggle.
