Bum. Mine failed last year - Pirelli P7000s cracked all the way around the inner rim.
I'm expecting mine to fail on one of the rear calipers. Handbrake ceased a couple of weeks ago, it's been freed off now, and it may scrape a pass, but I'm not counting my chickens.
Dunno about the headlight - sounds weird. Bulbs changed, so that only really leaves the reflector as the source of your problem. Only way to check is to take the headlight out and have a look. Rob Bell has some good destructions.
As you say, the lights dimming with be a bad earth somewhere. Can be a pain in the ass to find though.
They're getting hotter on the reg plates. I got a ticking off last year, but he let it through. I've put the legal one back on now - it's not worth the grief IMO.