After coating way too many firearms with Duracoat, the biggest thing I would add would be to make sure you do not use glass beads when blasting the parts. I use only aluminum oxide media, the glass beads aren't aggressive enough (in my experience) for the coating to bite into. Another thing to add, wear gloves, a quality respirator, and never never never wear contact lenses while applying Duracoat, bad things will happen.
When using an airbrush I will use reducer, and with a small hvlp touch up gun, I shoot it straight. If the ambient temp is under 70f. , I will also warm the parts with a hairdryer... does it help? Not sure but it was something that I started a while back and it seems to work fine.
As for as coating screw heads... If you take a piece of masking tape and stick the threaded side onto the tape edge, you can stick all of your screws onto the a piece of tape, fold the tape onto itself covering just the threads. This gives a way to hang them for easier painting as well as keeping the threads clear of over-spray. I use pieces of toothpicks or whittled down dowels to stick into the screw holes while painting to keep them free from over-spray.
For mixing I use syringes from a vet supply place. I use a 6cc for paint and a 2 cc for hardener. Brownells sells epoxy mixing cups that work great for mixing the Duracoat. I wipe mine after use with acetone, as well as thoroughly rinsing/wiping the syringes. These parts are very cheap, but I hate stopping a project because the syringes were full of old Duracote. I also use the small cocktail straws to mix with, although a small thing, I thought that wood popsicle sticks might absorb some of the product and throw off the mix.
A whole 'nuther topic would be the color/s you are wanting to apply. Some colors, with a multi color application, need to be sprayed in the right order to get the right effect. Dark colors aren't as important, but if you decided to pimp it out, you may need to start with a lighter color first to get it to "pop". Also there are clear coats to consider. I clear everything now, Duracote has a matte finish that it great for a flat non glare look, as well as a gloss for more shiny polished look. The clears not only protect the underlying paint, but also help to even out the sheen from different coats or different colors.
Let me know if I can help with any other info....
Dave