Quests do not reset, but bare in mind that each city-state will have its own quest hubs for various levels.

I have managed to get to 16 on my MRD and 7 on my ACN thus far by doing nothing more than story quests, fates & the hunting log. I haven't touched any of the side quests so that I can come back on another class and do them later.

Keep in mind that each class has its own separate hunting log to assist with leveling. I try to save leve allowances for Tradeleves whenever I can.