I don't see why they would. I have seen various decals installed and as long as you install felt on the sides of the pf they don't get scratched.

I wanna say action figures/models as toppers. Seriously it looks like a toy, because it is a toy.

To an extent both.

Part of it has to do with using polarized and non-polarized leds. The cheap ones tend to be polarized. This means they flicker twice as fast and that tends to be what causes the strobing effect. I have a jp that can be tough to play in the dark because it is noticeable. On the other hand I have used the same bulbs (ablaze concave white) in other machines (some DE's) and had no issue.

It doesn't really seem to matter on inserts. It really seems to present itself in places where you are getting the light unfiltered through something (insert, flasher dome) like the GI or spot lights. In those places I recommend polarized bulbs. They tend to be a bit more expensive, but the difference is night and day. It may still very game to game though.

Properly done I find leds to add to the game, but more importantly for me to keep the heat down and make it bearable to have 3-4 games on in a small room.