As I said, in addition once you have devotion, you can put in all the devotees, so that you have your deck with several unbalanced cards.
Not Really. Auberon gets engine pings to Wild Hunt units which you hardly use in R3 so it's usually just +1 to his entry value. And Winter Queen gets thrive which is good but not too many MO units have base 5+ power to really capitalize on it to an "unbalanced" extent. At least not the units you wanna be committing in R1 where WQ is played most of the time.
None of it is unbalanced. Every faction except NG has a dependable 7 for 4 now. Also, MO-OH deck, although very strong, has no ways of dealing with things like Elven Mage, Bincy, Saul de Navarette, Fallen Knight, etc. And it's tutorship is weak. These two things are somewhat exploitable.