Yes, you do want your rear speakers on the rear wall. And if the speakers can be mounted around 6ft above the floor then a cleaner looking and cheaper install would be to drill two small holes in the back of the speakers, about 1/4 ~3/8", depending on the size of the screw head, supplied with the EZ anchors.
The EZ anchors are then screwed into the wall to the same c/c spacing of the holes in the speakers. Then you just run the screws into the center of the anchor, leaving them stick out about 3/8" ~ 1/2". Then just slide the holes over the screw head.
Those anchors each hold about 80 lbs.
The speakers I have mounted that way are 38 lbs. I prefer the look of the speakers flat on wall, instead of using piot mounts
side surround.......................................back surround