You are fine with 2 x2 gig of RAM . Gaming doesnt need more .
You need to look for the lowest timings and lowest voltage . Some of the Gskill ripjaws RAM is budget , but since you havent mentioned which its hard to comment
The 850 watt psu is massive over kill . If you used a 650 watt you would still be in overkill territory for that build and have head room to add a second gfx card .
Looks like a pretty solid build. You probably don't need an 850W PSU, but the XFX 750W would end up costing you $10-$15 more since it doesn't have the combo deal. I can't give you that much help on monitors, but as far as I can tell, the a couple of the top brands right now are Samsung and Viewsonic. Asus and Acer sell a lot of monitors, but they tend to have more complaints about defects like stuck pixels and DOA monitors. The $200 left in your budget should be enough to get at least a Viewsonic.