Well the COD piece is actually attached to the front torso armor. It usually stays on right because my shoulders support the shape of it. Plus I know of doesn't look like it but the front is heavier than the back so the armor doesn't fall.
2nd question: well I'm not making the helmet In the reference photos. I'm making the Deadeye helmet. It actually has a pretty good line of sight.
Oh nice! The deadeye helmet is badass.