Long story short, water main burst in my home destroying my old setup.
And there are people living a life in Fear their water cooled system could leak xD
so.. first: IMHO the FX4170 sucks! Kepps kinda close to the i7-3770K in most games. But in some others you have significant performace loss! (
See Tests here)
so to your Problems.....
1) I have Two 7970 in Crossfire, gotta be around 10-20% more performance than two 7950. And if i set all settings on high in 6048x1080 (bezel corrected 5760*1080) i can't run all games with 60 fps! But if you lower the settings it works. So, if YOU want to go with Two 7950's.... did you ever run a Crossfire system before? Crossfire is a cool way to increase performance, but it also has it bad points, I.E micro Stuttering and Heath problems (not always... depending on cooler).
So why don't you just try running Single 7950 for a while, and if you don't have enough power you can just buy a 2nd 7950 later.
2) Resolution isn't a matter for PPP/LLL if you run 3x 1920x1080 or 3x 1080x1920 is exactly the same( If you have Bezel correction PPP uses a little more Peformance, but thats negligible) IF you run 42" i'd go with PPP your in Landscape the FoV would become to big.
3) The monitor runs FullHD, so 1920x1080! If you set them in Portrait its 1080x1920 ^^ simple. Gives a total resolution of 3240*1920 Bezel corrected resolution can vary, thats gonna be auto caluclated by Catalyst Control Center if you activate "Bezel correction"
4) You already had 3 Monitors right? most complicated is the "how to connect all monitors" there should be said: You have a FLEX edition, you don't have to care at all xD
Setup *should* work without any problems.