1. You CAN have a CT scan or other ionizing radiation with a pacemaker. It is MRI that you need to avoid. We scan and do xrays on patients with pacemakers all the time (I'm a radiologist). It is the magnetic interference of an MRI that can potentially disrupt the function of your pacemaker (or cause heating effects).
So that is not in itself a valid reason to opt out, though I am still not in favor of the extra radiation, no matter how small. It is not anywhere near the amount from a CT scan--I do believe that--but its relation to other things (cosmic radiation from flight, etc) I question, as do the experts at UCSF.

2. As for the shoes....no idea. We probably don't really need them off for anything. Why are the TSA workers patting down bare skin?