Yes it is.
Yes, but only from Rock Band 2 and up microphones. After a while Guitar Hero and Rock Band made their controllers compatible with each other (around the time The Beatles Rock Band/Rock Band 2 and Guitar Hero World Tour came out) which means any controllers from those games and higher are compatible
yes, the ps2 rock band controllers are actually ps3 controllers but they are ps2 compatible
Yes. All Rock Band games are compatible with all Rock Band controllers as well as Guitar Hero World Tour controllers.
The Beatles Rock Band Gretsch Duo-Jet guitar is not officially compatible with Guitar Hero 5 (GH5). The guitar is designed specifically for use with The Beatles: Rock Band and may not work properly with GH5 due to different game mechanics and controller recognition. Users looking to play GH5 should use controllers that are officially supported by that game for optimal performance.
I have not tried personally, but it is compatible according to the website
Yes, as well as Rock Band 3, The Beatles Rock Band, and Green Day Rock Band, I doubt it with Rock Band
Yes, you can use Rock Band 2 equipment for the Rock Band 3 game. They are backwards compatible with the game.
No, you can't use controllers between different consoles, but only with the same console. So you can use Guitar Hero PS2 controllers with Rock Band PS2, but not Wii.
No. Rock Band games on all systems generally only support controllers for the system being played on. However, PS2 and PS3 Rock Band instruments are cross-compatible.
Yes ...actually, no. It's a game all unto itself and you cannot transfer songs between the two. You can however use rock band controllers with either.
Rock Band is compatible with most game controllers, including the Guitar Hero: World Tour mic. and guitar. However, since the GH: WT drum set has cymbals, I don't believe that it will be compatible with Rock Band.
Yes.