400 sidequests or so, yep.
The ones you'll want to do are the ones from named NPC's. Those actually add something to the story or atleast let you learn something new about a town or certain characters. The rewards are pretty good too.
As for the material and monsters quests, start them, but don't worry about them. If you spend some time exploring you'll complete most of them automatically.
Also, most sidequests from named NPC's are designed to help you explore whole area's bit by bit, so doing quests is something you do along the way, not something you go out of your way for.