Re: 6800 GO driver programming
All I can say on this is, good luck. These days, neither nvidia or ATI seem willing to provide the information required to implement a full-featured driver.
You should be able to glean enough information from the Xorg nvidia driver to implement 2D support.
As for CG, this is an API. I'm fairly certain that nvidia wouldn't have dedicated CG hardware, and that the CG would most likely be translated to the hardware's vertex and fragment shader assembly code. I don't believe there's ANY information floating around about it though.