Boink117,
Usually you want lower voltage for doing corners and tight spaces. Higher voltage works better on big open areas, more powder gets to the part and 2nd coating is easier until you get to the corners and tight spaces.
Caswells hobby gun would probably work fine for 99% of what you're doing. You can always pick up Caswells new 12 week gun later.
Besides, you'll need to get some practice in
IMHO