See the sticky topic in the Techniques section entitled "The Complete Future" for all the information you need.
Future is nothing more than clear acrylic and won't cause any more problems with your airbrush than any other kind of paint. You can use Windex to clean your airbrush after spraying Future and it will take it right out. Follow the Windex with some plain water and then dry the airbrush thoroughly. The ammonia in Windex can cause steel parts to darken.