"Brian... there's the answer I was looking for. Once I set Aperture Priority and then f11... the only thing the main command dial does is change EC. (+/- EV) Correct? I was under the mis-impression that it changed shutter speed. Not sure I ever knew that before. Thanks."
Perhaps we have been misunderstanding what you have been trying to ask. When in Aperture Priority, and you use EC with the main command dial (to change the EV), yes, you are changing the shutter speed. That's how the EV is changed. In AP, you have fixed the f/stop so for the camera to change the EV it has to change the shutter speed. There isn't another parameter to change (forget about ISO for the moment) to change the EV.