I recently purchased a pair of the same speakers. Like you, I plan on installing them on the back wall. My take, after reading the Revel S30 manual, is that you want the speakers 20-30 degrees behind and 15 degrees above the main listening area.
If your listening area is six feet from the back wall, and assuming your ears are about 44" from the floor when you're seated and listening, then the 15 degrees higher would put the speakers at a height of 68" (44" + 24") from the floor.
I don't know that I can help with the recommended separation between speakers. I ended up with about 12 feet between the left and right surrounds.
Hope that helps. If you don't have Revel's manual, you can get it from their web site.