You must be joking right? were you dropped at birth by any chance?
Which part? Sense rom on 4.0.X had amazing stanby power usage. Or you mean that app is horrible?
Link to B1 from IRC: http://www3.zippyshare.com/v/45859598/file.html
Hahahaha just the thought of you eating a sandwich and crumbs falling onto the phone.
But yeah I got various bits of dust/ crumbs in the bottom bezel. Like they said, a piece of paper or a pin worked pretty well. Still an annoying oversight.
Most roms on the nexus 4 should be okay dirty flashing. Then if there are problems you can wipe everything.
If you backup your apps you should be able to reinstall them on the new rom no problems.
I'd say leave the back one on, as it seems to have scratched moderately on my naked one. Front still looks perfect. If you're worried about dropping then screen protectors won't do squat.