Original post updated to include outdoor shots after a black wash and added black details.
I used a mixture of spray paint and acrylics. I used a Rustoleum metallic silver, as well as Krylon Fusion gloss red. Toothpaste was used on the spots that I wanted to be paint chips. The black was acrylic, and the rear vents are also red acrylic (I forgot I needed to spray that) but it seems to be a good match to the Krylon.
As for the Stormtrooper helmet....I think this link will answer that question 
501st Legion: Vader's Fist