http://www.rockband.com/compatibility
Will answer all your compatibility questions.
IT does for Guitar Hero 3, World Tour and Metallica. Not for Guitar Hero 2
Yes. Any of the "Rockband" or "Guitar Hero" guitars will work for "Guitar Hero".
Any USB mic should work with Guitar Hero Any USB mic should work with Guitar Hero
yes, all of the guitar hero controllers are compatible within the same console. For example any guitar hero controller made for ps2 will work on any guitar hero game on ps2.
No, but in Guitar Hero 5 it works!
Yes, Guitar Hero 2 controller will work in any other guitar hero game same as guitar hero world tour controller can work on any guitar hero game, But you cant use xbox360 controller on another console guitar hero game.
Yes, it works for all the Guitar heroes that came after Guitar Hero 3
You can use any guitar hero guitar with any guitar hero.
Yes any Guitar Hero guitar controllers will work on Rockband.
I believe so. Rock band guitars don't however.
yes, all of the guitar hero controllers are compatible within the same console. For example any guitar hero controller made for ps2 will work on any guitar hero game on ps2.
Yes they are compatible with any Guitar Hero game