I believe orange peel can also be caused after the fact by below paints outgassing - but isn't that more a factor with enamels underneath something quick-drying, like acrylics?
As for dusting/rough finish, I'm convinced environmental factors can play just as big a role as air pressure and distance, if not more. Over the summer I had CRAZY dusting issues, even at ridiculously low pressures (5-10 psi) and very close distances. But it was stupid hot, and I discovered after the fact that my shop compressor had a broken drain *** and about a gallon of corroded water in the tank. Not sure which was the culprit, but here's a nice example I got spraying decanted Krylon gloss black onto a P-51:
http://i780.photobucket.com/albums/yy86/doogsatx/P-51D%20-%20Petie%202nd/60ba4759.jpg
Blech!