VOR, we have been waiting for you to come. Welcome!
Another Epic speaker for center is one option and not necessarily a 3.
Guess a 1 or 2 could be used as it is in HT setup if able to find a single speaker. Not familiar with the watts per channel of the Pioneer model to mains and center. Not sure which Klipsch center you have now but fairly certain the AVR has been enough.
Thinking your unit has preouts for connecting to an external amplifier.
My new to me CF-1'S want more power than able to put to it with 50 wpc so thinking of going at least 125 wpc myself. Thinking in your case 150 to alot. Have you tried just the 2 in stereo mode with the AVR?
As for ear level, the design with HF in the middle, think no elevation needed.
See someone more experienced with these chiming in...cool.