You're right about the "Gimmicky" approach of Black Metal. That's one reason I'm really into Goatwhore as of the moment (I think they're BM..?), because they don't take the Kiss Reject outfits road and just wear regular shit on stage.
Detaz, that's funny you're going as Abbath, lol. Make sure you can sing "Blashryk" exactly like he does. Make sure you also do alot of typical "Immortal posing" when people take pictures of you, lol.
COF sucks ass by the way. I'm a huge Dimmu Borgir fan, even though they've moved away from Black Metal into their own sound of Symphonic Extreme Metal * /me runs away, ducking tomatoes thrown by true Black Metal fans*
Well at least Dimmu can make the costume gimmick approach look kinda cool! I think it's because of their sound being more theatrical, thus they can have a more "theatrical" look.