I really like the ideas you propose, especially the multi-role queue (even if it would still fall on healer or tank most of the time)

The mentor system does need a overhaul, and I suppose my own suggestions would be:

Add a reputation similar to how BDO has commendations in chat, to elaborate, Players get an icon next to their name that changes with how many commendations they have recieved. It helps players that are actually helpfull and veteran stand out

For the 2k+ Rewards what comes to mind is archievement voucher rewards, Adventurer plate decorations, new title, maybe a new glamour too

And on a bigger level I would like them to require level syncd Ex clears for the mentor unlock (To avoid mentors who did it unsync and instantly leave when an ARR or HW extremes pops)