With respect to Ambient Occlusion support in NVIDIA control panel it comes from within the driver. I just read on the Nvidia latest WHQL driver the following:
"Visual Quality
* Adds ambient occlusion support for one of the most popular games of the year: Starcraft II: Wings of Liberty. Ambient occlusion improves the quality of lighting, shadows, and depth perception in many parts of the game. Learn more on GeForce.com."
They also say its around a 30-35% performance hit:
http://www.geforce.com/#/News/articles/starcraft2ao
So I guess 1C needs to "liaise" with NVIDIA to get COD listed then hopefully it can be simply turned off that way.