Just a small tip to help you along. Try to find a regulator that reads well in the lower range, 'cause most of your airbrushing will be done between ten and thirty pounds of pressure. Some of them are intended for air tools and other things that require high pressure, and are much less useful for our application.
If the place you purchase the regulator and trap doesn't have compatible fittings, a good hardware store can set you up with adapters for most any thread combination.
Happy modeling!