1) Probably too early to tell, not enough concrete data. I have the S23A750 which is the same panel and I am very impressed.
2) Use the supplied DVI-D cable and plug it into a DVI-D port on your 590 and you wont have a problem.
3) There is a 3D Vision Emulator that apparently works. I don't know anything more about it though. Here is a link to the emulator: http://hotfile.com/dl/111389928/3d22e5e/3D-Vision-Emulator.zip.html
4) Nope, I use a ACD + S23A750 no problem.