You don't need one. The Wii Remote connects automatically.
No it doesn't but if you have broadband or something, you can connect it up to your Internet.
The network adapter
There is a Guitar Hero for Wii, but it isn't exclusive to Wii.
No, not for Guitar Hero (Wii) nor Rock Band (Wii).
The Guitar Hero guitar will work RockBand for the Wii, but may not work for Beatles: Rock Band.
No it can not. The Nintendo wifi usb adapter sends a signal that only Nintendo products meant to connect to wifi (such as the DS and the Wii) can pick up. Xbox and other products of that nature can not pick up on the wireless signal sent out by the usb adapter.
No.
Sorry, no.
yes!
depends what console you have, it it is a wii then you can put in the wii remote into the controller, but if it is ps3 or xbox then you need a signal receiver that you plug into the console, it also depends what guitar you have
Yes, It should.
For wii you don't need the guitar, you can just use the controller.