Wow, Five, that's a lot of question!

I'm no expert, but I've found the same thing - GB is NOT a good program for chord changes.

I think I can help with some of the "other issues":

(1) a loop has either major or minor tonality - you can't "move" it from one to the other - you've got to use a different loop

(2) same concept as above - if the "loop" was based on a seventh chord, you can't "move" it to another chord type (no way to eliminate a flatted seventh note from the loop and use it as a major chord)

(3) and (4) I don't believe you can "shift" a loop in the middle of it - that is, if it is a two measure loop, I don't think you can shift it after one measure

Hope that makes some sense. Good luck

Bruce

Macbook Pro 2018
2.6 GHz 6-core Intel Core i7, 16 GB RAM
OS Monterey
BIAB for Mac 2022