What else, important, do I need to check? Keep in mind, this is a $500 car.

Leaks.
Exhaust fumes.
White or milky oil.
Oily radiator fluid.. Bubbling fluid.
Does it go at least 10 miles? (fuel tank vacuum)
Any grinding on shifts?
Heater core work ? (very very cold where I live)
Engine knocking.
Does it get to and stop at about 195ºF?
Does the seat belt pretensioner work?
Handbrake. (M5)
Salvo title / bent frame?

Thanks.

 

That sounds about right but don't expect it to be perfect for $500...