I have Solved the problem. All Radeon 6-series cards should work, and specifically, a Sapphire 6970 WORKS! The Radeon 5 Series does not work with the display-port Cinema Displays except for the Eyefinity 6 models. Since display-port is basically packet like communication, unlike DVI and VGA, issues can arise with early and inconsitent implementations.
I have no information on Nvidea Cards. I have heard mixed reviews.
Brightness control is available through the brightness driver that Apple provides for Bootcamp. You don't need to have a Mac to use this driver: any windows machine.
Windows 7 automatically enabled the speakers, microphone, and camera in the display.