Well I do not have a coin to display, but I do have a Corinthian Style Helmet that any warrior would be proud to wear. Obtained at a Greek Festival in my area many years ago. Great dust collector, but I like it.
No, my head would get stuck, firemen will come, jaws of life will come out, my head stays in helmet......
I don't know, but wearing that into battle seems like wearing a sign reading "get me, I'm important".
Speaking of helmets, does anyone know if the soldier emperors of the latter Roman period actually wore them into battle? I am specifically curious about whether the radiate crown (specifying an antoninianus) would actually be incorporated into the helmet like they do on the coinage. (Probus, I am thinking of you, buddy!) If they did wear them it might cause unwanted attention as @kevin McGonigal suggests!