LED headlights and light bar.
#3
Probably not. But there are not blue or always on the bright setting so I think they will pass. The light bar isn't always on either. I'll have to ask one of my CHP buddies and get back to you. But they do work great and only for only 60 bucks.
#4
IF DOT-compatible, they should have a sharp cut-off so they doesn't scatter the light, they light the ground and things in front of vehicle, and not blind drivers in front of you.