To answer your questions in order:
Camo suits work just like mimetic armor. The details are in TacOps, page 318.
Armor on top of sneak suits? No. Only one type of 'armor' at a time, and camo suits count as 'armor'.
I think so, yes. Might want to check the rules forum to make sure.
Tech Manual, pg. 351. 99% sure you want Semi-Portable PPCs, since Support PPCs are small vehicles unto themselves.