Question 1: I do like your suggestion about global play. It would have to be done through your battlenet though and they shouldn't just have all servers global. I have played other games like SWtoR and CoH that have all region servers in the same area. The problem with that is the do Maintenance at the best times for the US players, leaving many players having it go on during their prime time. I would not like WoW to go the same way.
Question 3: Removing Have Group Will Travel gets people back out into the world? I don't think so. I would hardly call the limited time it takes to get to a raid instance getting players back out into the world. In my opinion it is just nothing but an annoyance. I don't think removing this power will give the Intended effect.
I do agree with you in the regard that it does make raiders a little late though. Raiders should be already there at start time, not waiting for an summon. I do however feel that the negatives of removing this do outweigh the pros.