http://www.celicasupra.com/buyingtips.htm
there are some good tips on that site, look for that rust spot too, take car of that, if not it'll just get bigger, check all the rust spots the site says.
about the mech, not sure just ask him to see if the cars okay i guess. i threw so much crap at my supra 85 its all stock except exhaust, ohh and suspension. i drifted, raced, daily driver. anything will come its way. just make sure to keep it maintained like any other car.
and im not sure about the offer, check it up on cars.com