Wow you are purchasing the exact system I own. I have a denon 2807 reciever, RF82s, RC62, RS52s, and RB61s for rear Surrounds along with a 3.3 HSU.
I think this setup is perfect. If you can afford it I would get the RC64. You can never go wrong and sometimes(although not often) I find the center speaker lacking(althouth I have been meaning to run it about 1 db hot).
The RB61s match just fine with the entire system as rear surrounds. I would not go with WDST speakers for rear surrounds. The RS52s are neither bipoles or dipoles. They are proprietary Wide Dispersion Surround Technology that Klipsch uses. I have tried them as rear surrounds and like the direct much better.
If you want to see my setup go here. I have pics. http://www.avsforum.com/avs-vb/showthread.php?p=10823268#post10823268