For any discussion of Future, I like to reference Matt Swann's page at his site, Swanny's Models, with his info on Future:
www.swannysmodels.com/TheCompleteFuture.html
Here's my own experience with Future:
I brush it on by hand, or apply it via the airbrush. It's self-leveling, but I have learned to go easy and apply multiple coats, rather than a lot at once, because it will pool or drip, if you put on too much at once.
I use Windex to clean brushes and the airbrush, followed by water.
Windex will dissolve cured Future, in case you do get a dried drop or streak, or need to undo it. The ammonia is the ingredient that dissolves the acrylic.
For decaling, I like complete coverage, but not too thick, because it is possible to build up too much acrylic and obliterate fine details
Future is great for fixing scratches on clear parts. You can use polishing pads to sand out scratches and then dip in Future, to fill the polished area
Hope that all helps!