Wow sorry for the late response... didn't see this one
We have (As stated above) behind the head headsets and above the head headsets. I plan on doing a full write up on our headsets and the differences with photos and such to make the choice a little easier than it has been in the past.
Our over the head headset feels more comfortable but doesn't stay on as well as the behind the head headset. The behind the head all come in black, red, blue and carbon fiber and the over the heads just come in black and carbon fiber.
Our helmet kits can be mounted in an open or closed face helmet, just as long as the ears are covered
Radios are connected through the intercom if you have more than one person but can be connected to a single person without an intercom. As stated above as well, the headsets have a 3.5mm plug so you can connect a ipod, mp3 player or sanner to the headset.