Indeed, however While not being a purist, I find it difficult to procure stickers, let alone use them. Basically I can easily find printable decals, but I have yet to find prinable vinyl sheets.
I tried with black and I find it to "pure": gray looks a bit weathered. As soon as it is possible, I'll post a version in black next to a version in dark bluish gray.
Yes. I use an an articulation system. The centre wheel is sliding on the frame and using universal joints causing the outside wheels to turn. I made a mock-up to see whether it works.