Great topic!
1. I think this could be partially beeing solved just by removing the option to let others join your group after it has been made. Maybe a popup at the start of the GIM what teamsize you're choosing and who you want in it. Once selected, it's locked.
2. I'm in favour of a non-donator playstyle for all GIM players, Fair for everybody, no pay to win. (Sorry for all you out there with mom's creditcard).
3. No solution for this so far besides a lending system instead of a trade system. Yet this would give problems with items taken to wildy,
