Rich -- you're most welcome. If it's a double-action, that takes a bit more learning but again becomes second nature, as the fore and aft motion of the trigger controls paint volume by moving the needle assembly back and forth, while the up-down action controls air volume (full bore on both for cleaning!)
Primer is not strictly necessary but it will show up where your seams need more work, and that's always valuable. On scratchbuild projects I've used two or three coats of Humbrol #1, an excellent gray primer. I read many years ago that Humbrol grind their pigments much more finely now than they used to, which improves spray painting. If the paints are properly thinned and sprayed gently (not blasted on), they should lay down like velvet. I use acrylics preferentially now because of the toxic nature of solvent based paints, but remember enviously the application characteristics of enamels. One day I'll have a spray booth, then I can use them again without being at the mercy of the weather or gassing myself and the family...
Masking: Let the paint dry 24 hours for safety, there's no rush on a project like this. The RAF birds were hard-edged, so do you have a plan in mind for masking the wavy camo demarcations? Also, priority of application -- the rule of thumb is lightest to darkest, but enamels are pretty dense and you can actually spray-apply them in any order, it just takes more of a light colour to cover a dark than the other way round.
Preshading -- it's taken me all these years to try it and now I'm hooked. Load up some black, acrylic will do, it makes no difference, and run over the panel lines with a tight-ish line (precision not necessary). The show-through is subtle but appeals to the eye!
Are you planning to clear-coat for decal application and final finish? There'll be much more experienced hands at clears than me in this build, but I can strongly vouch for the Microscale products -- check out my product review of their satin finish on my blog (address below, latest post).
Cheers, Mike/TB379