Just to comment on the airbrush portion of your question (since I do a lot of scale modeling and hence work with a lot of airbrushes): in general, you'll want to get the cheapest name-brand airbrush you can find. I specify name-brand because sometimes the generic ones simply don't work. Cheap though, because from my experience applying Duracoat, you'll only get to use the thing once before it cakes up inside and you'll not get it clean for a second use.
Badger is a good name-brand company that you can trust to work ok. Probably want to look for a cheapo single action, though if you want double action is available too (single action allows you to control airflow only by how much you press the trigger, but double action does this plus allows varying paint flow as well by pulling back the trigger after it's pressed).
Most craft stores will have some form of Badger airbrush for around $20-25.
As to Duracoat: from my experience, the stuff sucks. It ends up looking like spray paint on a rifle (not sure about a stock), and it wore very badly on my gun. A year after I'd applied it every little nick had bright silver shining through (I applied it to a barrel that was in the white). About a year and a half after the Duracoat I just bit the bullet and sent it to a gunsmith to have it stripped clean and blued. Rifle looks 100% better.