Who are you going to be? I would suggest some kind of clerical spellcaster: you don't have any divine spellcasters in your singleplayer group, and you will find out how much you need them as you get further through the game. In order not to spoil the game for ya: are you sure you want all those different alignments and personalities in one party? You've definitely got some differing worldviews in there.
That's a pretty cool multiplayer party, but why don't you consider a Fighter dualled to Mage? That way, you can have some really exotic characters (Berserker=>Mage, Wizard Slayer=>Mage, roleplaying that will be fun.) [img]tongue.gif[/img]