There are two kinds of air brushes one is a manual one where you use your own breath as the source of air, and the other is with an air source, such as an air compressor. Which is the most common type .You can use all types of paint, enamels ,acrylics and lacquers. But they all have to be thinned down in order to work in an air brush. There are not that many moving parts in an airbrush. But they have to be kept very clean in order to work properly. You have to clean them real good after every use,if not you might just as well through it away.
As you push the trigger on an air gun it pulls back the center piece that has the tip connected to it .allowing the paint to be distributed out in a spray form. It either sucks the paint up from a small glass container. Connected to the bottom of the airbrush. or from a drip cup located on the top of the airbrush. Two types so you will need to decide which type you need or want. They all come with assembly and dis-assembly for cleaning cleaning instructions. So if you buy an airbrush that has a constant air flow you will need a air compressor. Which generally run from $69.00 on up, unless you can find a used one. I hope this info helps you somewhat.