I'm 99,95% happy of the stencils. There are some spots that are not lining up perfectly with the surrounding areas (ex. dome and red rim, mandibles and cheeks, and so on), but not a big deal. I tried to color match the stencils with the real helmet in a not too bright tone and I think I nailed most of the colors:
There are color variations on most areas, mostly because one of the main colors was painted over an existing color (some of these are touch-ups to hide or tone down the silver weathering), thus a new shade had enrichened an already perfect paint job:
I'll start working on the color separation for each area.