You got a good deal! I don't need another airbrush( I have 2 H models, A VL, A Talon Gravity Feed, and a pro modle Aztec), but if I did I would check out the local Michaels!
Acrylic enamel is water based. You can spay it over either primer. But you will often have problems if you try to spray oil based enamels, or lacguir over the acrylic.
I actually got a little work done on preping my Traditional Chopped T, inspired buy Bad News as seen on Rides. This is the first work I have been able to do this year!
Good work on the weathering.
You aren't the only one who has learned something from Dr Cranky! Even after 57 years of building models, I have learn some better ways of doing things from Dr Cranky!