I can't answer all of your question. I've only removed 2 63 window shields so far. The first I broke.

I'd cut the old off of the outside of the window. I thought I was carefully lifting the window out of the seal and it was going real good. Then I jiggled a little too hard, gone. I would really recommend 2 people, to do the work. I've installed other windows, VWs, Tenant sweeper, not wrap arounds. They've all be PITA. It does take some experience to get the glass to slide into the new seal. Your suppose to use a rope or cord in the new seal to pull the lip of the seal out for the to slip in. That sounds good and it does help, but not easy to do, without some experience.
Larry
68 C20 327 daily driver
63 C20 292 Camper truck
65 C10 ? Custom Cab AC,PB,PS,$flasher