A) I'd say stay with Warlock till you get your Moon and Fiend spells, especially the higher level ones.
B) Not sure what your party make-up is, so I can't tell too much about the Lizzord...use him to "fill in any gaps" that you may have. Samurai is always a good choice, for the Sun magic...you just can't have enough firepower in this game, what with all the vegetation! Ranger or Ninja will work well, too...and then there's always the coveted "Assassin"....
-Sazerac