I paint them on the sprues as if you are careful snipping them off there is little to no cleanup required. Once painted and washed etc they go on the painted model lower hull.
Paints depend on a lot of things but I’ve found a system that works for me.
1 - black matt primer, usually rattle can or Mig One Shot by airbrush.
2 - Mig Dark Tracks base layer
3 - Metallic wash made of 25% Vallejo black was, 25% flesh wash, 25% pale grey wash, 10% Vallejo metallic polished steel paint and 15% thinner.
4 - wet pigments fixed with hairspray.
5 - dust layer where appropriate with a thick wash of yellow or dust wash.
6 - cleats and track edges picked out in either 6B pencil or lightly brushed with polished metal raw pigments, depending on mood.