I would've said level 30, but yeah once you get a few dungeons under your belt, you should be able to decide if you're into it.

It can definitely feel like an overabundance of quests when you're just starting out. If you prefer, you can stick to just...
the main story quests
the "important" ones (little plus sign next to the !)

If you're overwhelmed by the quests, just skip most of them (they aren't going to go anywhere, and you can do them later if you feel like it). Generally speaking, the boring side quests are mainly there to help you level other classes.