Alright so first off what is your price point? I am assuming (correct me if im wrong) that you are running on a fairly unlimited budget. The Xenon will kick most programs in the ass if you are running them individually. The only bottleneck with it will come in with your RAM, which is currently so cheap right now is laughable so you should be fine on that front.
The graphics card situation is an interesting one. I am personally an nvidia fan, have always had really good "luck" with their cards. People all over are raving about the 7990 though and from benchmarks it is a very powerful card. If you want to go all out the GTX TITAN will run your 5760x2160, but there are other factors that will play in. For instance, what are you using this setup for? Do you want to project your game across each screen in crossfire? If so, do you want to max out resolutions in said games as well as aliasing. If so you are going to need more juice in the graphics department. Now I ran the whole gtx 460 in sli when it was the best budget graphics an enthusiast could dream of, but even with a fairly well lubed system and drivers I still had hiccups and from my understanding in building desktops every multi gpu solution will have hiccups now and again. This is not to deter you, heck you could have built one already for all I know. I just wanted to make sure I cover my bases with my post.
As for off screen gaming you have a few options. The best option in my opinion is to set up your desktop to run its own server. This way you can tap into the power of that server and have your powerhouse workstation do the heavy lifting and then send you the results through wifi, ethernet, firewire, etc. I dont have the most experience with this but can recommend a few books and articles that will help get you started. I personally use "Splash top." I have an Asus Nexus 10 and I stream my desktop through the Splashtop ap onto my tablet, basically using another companies server to tap into my workstation. It is all doable though.
Finally ssd solutions, You can buy a RAID style system to set your SSDs up in but I personally just made my own and have had no problems with it. My budget wasnt quite as large as it seems yours is so I have a 256 Gb SSD for my OS and other things like CAD, Light Room, Final Cut, etc. and then the rest of the space is 1 Tb hard drives. It works fine for me. Your bottle neck here will probably be either slow esata connections with your mobo or the right speeds of the SSDs you choose, neither of which will be too noticeable though.
Hope I helped with this small biography I have written, if you need any more help feel free to pm me.
Cheers
-Preolt