pick out quadro these are the best cards for rendering,3d work,office, autocad etc...
CUDA™ is a parallel computing platform and programming model that enables dramatic increases in computing performance by harnessing the power of the graphics processing unit (GPU). http://developer.nvidia.com/what-cuda
in other words, depending on the application, the software can use the cuda cores, the same as stream processors, to help the cpu complete a task.
after affect depends on openGL whereas premier uses cuda. it would be a good idea to google around or to read the differences on the adobe forums to find out how/why. a good start is: http://forums.adobe.com/thread/632669
not to be unfriendly but what you ask is a lot of information that would make my head hurt . .