Mage is incredibly indispensable class to have in your crew, for healing and buffs... Like always, it starts out the weakest - useful for healing only. While on the other hand Sorcerer is more of a devastating attack and debuff oriented class.. There's also some mix classes like Magick Archer and Mystic Knight, but I get the feeling you'd rather avoid close confrontations, so try the Magic Archer which is a good magic class if you ignore the fact that your catalyst looks like a bow..
And while you might feel otherwise, I'd suggest you keep another Mage in your crew for the start. Have them focus on healing while you get the hang of offensive spells.
Oh and yes, the game isn't easy at first, even I struggled in the Well, and I was a
despicable Rogue.