DVI-I vs DVI-D:
They are identical except DVI-I also contains pin-outs for the VGA (analog) adapter. So there's no difference connecting to a DVI monitor.
There's no problems that I can see. Your monitors are only 1080p so you can support three monitors easily in Surround.http://www.geforce.com/hardware/technology/3dvision-surround
No issues I can see other than deciding whether to use Adaptive VSYNC, Adaptive Half VSYNC, or VSync off when you can't maintain a 120FPS frame rate in games (or 144Hz).