hahaha sure. on the things i told you to look up, so you can learn what it means to be metal...
here are some good clips from metalocalypse
. to put it in context, this is the birthday party for the band's bassist.
another set of clips from metalocalypse
. these should be self explanitory, so have fun.
Concert by GWAR
. The only thing you really need to pay attention to is their mannerisms and dress. this is definitely the epitome of hilarious metal.
And an iron maiden concert
. pay attention to the crowd: this is the army of metal.
Basically for armaments, bring out the outlandish medieval weaponry and large blunt objects. If you can figure out how to make lego guitars, drumsticks, and other musical instruments, that would add variety to a battlefield as well. a thrown cymbal is incredibly lethal.
vehicles would be few and far between; fans are mostly just traveling on foot. I'd probably just suggest making a tour bus covered in as much morbid crap as possible, and a few motorcycles (or murdercycles) for good measure.
for clothes, don't fret too much. gothic medieval warlord crap for the band themselves accompanied with just t-shirts and jeans for the fans is fine. if you have police minifigs, their torsos would make ok bodyguards, but make sure that the face is that of a badass. Roadies (the guys that carry around all the equipment for the band) shouldn't be too hard to make either, but give em a little bit more metal than the fans (a small piece of armor should do it).