I use a small paint brush to apply the Future coat as a little bit goes a long way and having a small amount on your brush ensures that you wont get any pooling. I would also suggest you apply the Future in stages for example on the Mustang I did the roof, hood and trunk and let the Future self level and dry, then I turned the car on its side so it was parallel with the table and did the same procedure.
Pratice on plastic spoons until you are comfortable.
I have also tried to run Future through my airbrush and had terrible results, I found the best way is applying it with a brush.
I also agree that Future is a lousy top coat compared to lacquer.