There are many companies who make headsets for Xbox 360. Here are only a few headset companies I know of:
Turtle Beach - The best headsets available
Venom
Tritton
No, xbox 360 headset can only work with the 360.
All headsets are compatible with World of Warcraft.
Headsets for the Xbox 360 range from $10 to $60. The cheaper versions tend to be wired and are not manufactured by Microsoft. The more expensive headsets are wireless.
Plug the chord of an SPECIFICALLY XBOX BRAND headset into the bottom controller.
no
Yes.
Yes
Some brands of microphone headsets for the Xbox include Sennheiser Over the Head headphones, and Turtle Beach Ear Force X41. Other headsets that work with the Xbox includes Mic earphones, and KMD 360 Pro Gamer.
Yes, there are many brands for that. One brand is called Turtle Beach headsets.
Nope.
It depends upon what headset you have. Most bluetooth headsets are compatible with PS3, but old ones may not have as good sound quality. Also, most USB headsets will work as well.
The Xbox 360 headsets are quite cheap, just buy one.