Speaking directly about the FATEs, my guess about the experience from them ties in with how it worked in 2.0 at first. The FATE xp wasn't great, but when you hit 50, you got a buff to all FATE xp gained. My guess is HW will give you increased FATE xp from 50-60 once you get your first 60, providing you with something to smash on while you level other jobs and are sitting in the dungeon queue. That's just my guess, though. I don't know if it's actually the case.