The brake light can come on if there is a problem with the brakes. That is probably the case. Maybe a bad proportioning valve or something. Unless you are getting a stellar deal (under $10K with decent mileage) I would take a pass on that one unless he will let you take it to a mechanic first.
As for the MAF, I just had my recall sensor put in last week and promptly modded my intake, so we shall see how durable it is. When the MAF blows, the car will not run properly until you disconnect the sensor under the hood. The car will then drive in limp-home mode where you cannot go over 3500 RPM. The new MAF costs $50.00 from the dealer and is easy to install if you have safety torx bits. A blown MAF should not damage the engine. FWIW, I have had my car since July of 1999 and it had the origional MAF when the recall happened. I have never blown one and I had a K&N filter in the stock airbox, with a gasket in the secondary airbox.