Do a search in the monitor forum for Betson and you will find a long thread on the geometery issues. In short, 15khz has some things that just can't be fixed (squished sides), but higher res modes like 640x480 are fine.
As for the red spot, try moving your cab away from the wall, and/or turn it 90 degrees to see if that takes care of it. If still there, then possibly something inside the cab (like a speaker) is causing magnetic interference.