So you want the 100 rep achieve?
You want to do the 20-120 leveling for the transmog and mount?
You want to do all of this on the new allied race?
So.. Level up a "boring race", unlock allied race, then shift over?
Or you could simply level up a toon, unlock allied race, racechange your toon over (so you keep ALL progress on the now new allied race), THEN you make a new Allied race and level him from 20-120.
This way you get to keep all your progress on your main, AND you unlock the tmog and mount. How fucking hard is it?
Is it correct, that you can create a DH on a fresh account(no more level 70 requirement)?
Two totally different things. Allied races were included as a perk or selling point to this expansion. They should be achieveable by completing current content,they are not a boss drop from content fitting the reward.