The PC speeds can't be expressed in RPMs, only OPMs (oscillations per minute). The PC oscillates, or wobbles.
I do all of my polishing on speed 5 or 6. With cleaners like AIO, I use the PC on speed 3 or 4.
I very rarely apply any LSPs with the PC.
As far as pads...
The choice of pad really depends on the severity of the defects you're trying to remove. If I am tackling some bad swirls, I'll use the yellow or orange Propel pad with SSR2.5, then sometimes followed with SSR2 and a green pad.
For cleaners like AIO or GEPC, I use a blue or green Propel pad.