The last question is the easiest - I would go with nVidia because their CUDA processing engine accelerates many of the applications you use. I know Adobe CS5 and Maya take advantage of it but don't know about the rest of the applications you listed.
Adobe CS5 added acceleration for multiple applications with the Mercury Playback Engine which is designed specifically for more recent nVidia cards with the CUDA feature set.
http://www.tomshardware.com/reviews/adobe-cs5-cuda-64-bit,2770.html
Third party review and recommendations for use with CS5 (the card list starts about half way down the page)
http://www.studio1productions.com/Articles/PremiereCS5.htm
CUDA (see more info below about CUDA) supported graphics cards (note that the GeForce or mainstream and gamer cards (for desktop and laptop PCs) are listed near the bottom of the page:
http://developer.nvidia.com/cuda-gpus
nVidia provides information touting how much their cards accelerate Adobe CS5, including general description about CUDA with internal links to more info for advanced users:a
http://www.nvidia.com/object/cuda_home_new.html
Here are a couple of reviews on workstation cards you might find informative:
Workstation Shootout: Nvidia Quadro 5000 Vs. ATI FirePro V8800
http://www.tomshardware.com/reviews/quadro-5000-firepro-v8800-workstation-graphics,2701.html
AMD FirePro V9800 4 GB: Eyefinity Meets Professional Graphics
http://www.tomshardware.com/reviews/firepro-v9800-eyefinity-quadro-5000,2780.html
The choice between workstation vs. gaming cards is a little more difficult. The higher end gaming cards are very similar to the lower end gaming cards, the difference is primarily in the drivers and service. Workstation drivers have been more finely tuned to the kinds of work done in WS applications - but this can have a signficant impact on performance for those applications. Morever, with the higher price you pay buys you better, generlly quicker support for dealing with issues.
I think the choice must depend on how and how much you use the cards. If you use the applications for several hours a day, the higher productivity of the workstation station cards may pay for the higher cost several times over. Otherwise you might do just as well with the gaming cards.
If you decide to go with gaming cards, you might find some helpful information on upgrading video cards at upgradevideocards.com, but they have no information on workstation cards:
http://www.upgradevideocards.com/index.html
