Sounds like you're into very heavily threaded work, the Phenom II X6 1055T would show up to 50% performance increases over the Phenom II X4 965 in these types of applications.
As for the motherboard, currently no desktop end AM3 boards have been equipped with four memory slots.
To answer your questions:
Monitor - I don't know sorry.
If you feel quick loading times are worth the extra $, then go for it. Otherwise I wouldn't really invest in one. Apparently the HDD/SSD hybrid from Seagate, the Momentus XT, isn't that much faster than a normal HDD although it does show some improvement.
If you're talking about the Phenom II X4s, the C3 965s can reach 4.0 GHz or so, while I've heart the X6s can reach 4.0 GHz +. If you want to overclock then you will want an aftermarket cooler. How loud the cooler will be depends on the fans you use.
650 W won't be enough for GTX 470 SLI, but currently no AM3 boards support the use of two GTX 470s, with the exception of the MSI 870A Hydra. You might want to invest in 2x4 GB RAM kits if your work is very RAM intensive.
And so far I'm very happy with what I'm seeing. All of the strange judder and other DVD weirdnesses seem to be gone now.
I don't think your budget is big enough for the SSD right now, and when you get one it needs to be large enough to take those games that really will benefit from it, like Crysis. I think 120GB minimum.
A single non-overclocked 470 can pull up to 230W, while a pair in SLI with moderate overclocks can hit 450W (although less on average loads). Throw in the rest of the hardware and I would not recommend the PSU. A single 470 is pretty good though. Perhaps you should save some money on the board and get a good 870 or 880G board.
You can OC the CPU well and easily, and yes you should get a cooler.