Looks great! I'm working on a similar project at the moment.
SM, I usually just wash the parts with mild soap and water, just to get any potential casting residue off of them. It's been rare, but I have had problems in the past with paint not taking to plastic parts because of residue on them. I usually use a mix of acrylics and enamels, depending on what I'm painting. The enamels seem to have better capillary action for some smaller things, while I find my Tamiya acrylics are great for just about everything. I'm a big fan of water wash-up too! Just don't buy any expensive natural hair brushes, they tend to not like water. :lol