Camera
I use a VIO system that I purchased from a fellow racer. The system is very rugged and uses a good camera. Sports Car mag. (the SCCA mag.) did a review and liked this one best including picture quality. It is easy to use and has a remote to allow easy on and off so you don't get lots of pit lane stuff.
The system is, reputably, used by law enforcement and the military and is water resistant. I use it with a suction cup mounting system in the GT to attach the camera to the inside of the windshield and to the rear glass for a cockpit view. Personally, I like the windshield mount best as it gives more front view and the cockpit view doesn't have good picture quality due to the differing light levels. The standard system is self contained but can be powered by the car if you want.
The system is about $700. The guys I bought mine from are racers and great guys. I am not sure about posting their information on the site so, if you want their contact information, send me a PM and I will pass it on to you.
Big Dog