Thank you for the reply Keltoras. 
This does answer my questions.
I do have a few more questions:
Going back to my original post,
What will be done to combat boosting overall? While this upcoming LFG tool seems great, I can already see it being filled with advert for boosting groups.
Edit: Kaivax provided a response to that here: Adjustments to Dungeon Creature Behavior and Group XP
What about underpopulated servers? I would assume this tool doesn’t bring cross realm into the equation, is there anything in the works or on the drawing board to help players on smaller servers?
Does this mean a mage could queue as a tank or healer? If so, why?