Make sure to use plastic specific paint. I used some of the Painters Touch 2x (Says ok for plastic on the label) for my belt and had HUGE problems with the paint not adhering to the plastic as well as not curing properly. Krylon fusion for plastic worked great on the other pieces. I didnt like the "Satin" finish the fusion ends up with. it was more of a semi gloss so I hit it with a matte clear coat which took the luster down a few notches.
For the finish ike the other said, go with what you like. I went Satin for the armor and Gloss on the greebies. The finish works out well with the SC sticker kit since they are gloss black and accent the satin finish very nicely. .