I should use synthetic-based paints, very difficult to find in cans.
why synthetic-based paints? can you find the colors you need for the spray job in "normal" paint cans or are they produced especially for you?
Spray painter or foam rollers? This is the question

hmmm, difficult choice you have to make. i
haven't had the best experience with those spray painters on my Joust 2. IF i had to do it all over again (which i eventually will with another cab), i'd get a professinal system with a compressor, although i have NO IDEA which one to get. as always, the market is gigantic and you have to look thoroughly.
perhaps someone else around here is better versed in this subject.
of course you could always ask at klov, but the suggestions those guys make are american-based and you will have a hard time finding those items over here, therefore a european suggestion would be better. i'd be interested in this as well!
btw, don't rush it, scr33n. you've spent so much time (and money) into this already, don't ruin your job with a poor choice of "weapons"