Stanley's reaction may only be in response to Parson leaving GK - his face wouldn't fit very well in panel 4.
I agree with Billiam and Walt (and Ansan) that
A: it's George Harrison (no epaulettes on that cover, wrecan) and
B: he's a GMtTA, and so got into position to use that scroll (which happens to be a different color or a different scroll entirely as compared to p57; blue now, red before) and help Parson.
Assuming that he is not privy to Maggie's message, I expect he'd have to be a Dirtamancer, as no one else in the Magic Kingdom detected "Mind the Gap". I think he's a Hippiemancer despite what's been said, just take a look at his Abbey Road days. The man was a total mystic.
Kaed, I bet it will come back to bite us (it kind of already has with Vanna) but I don't think we're looking at Jeftichew, Spenser or Bowie anywhere in the recent updates, and I'm going by the name associations suggested by the wiki. I'm looking forward to seeing them in action though. Point of interest, Vanna has solid black eyes, and so does Stanley, however Sizemore does not. What's been said about Signamancy and Tribes and all that?
The other 'mancer in panel 5 is bugging me - I don't recognize that head decoration, but it is pretty striking - and I don't think it's Pinhead.
Also, incredible sound effect, yes. I also expected Sonic Boom or Sonic the Hedgehog, but "Drive-In" is punnier here. Any more "Jason" name theories for Tram's knights now that we're seeing more clearly?