I don't play WE, so i'll answer about the "resin or metal"? Resin (finecast) is easier to work with, but some people report problems with it, so I advise you open the blister at the store to check if it's alright. Black and white primer are both good for green, it depends what effect you want to achieve. Black primer is, imho, easier to paint with, but the general tone will be darker by default. can't help you with the paints, I'm not yet familiar with the new ones.