[ister]

I'd go with F/T. You have plenty of spell casters, and I don't find two thieves to be THAT redundant. As your tank you want detect illusion skill to be up at 100% quickly so he can take down all the mislead and project images that enemies love to cast. That alone frees up spell slots. You then give him stealth so he can backstab to open combat, and leave locks and pick pockets to Jan. And of course the F/T CAN (and usually should) wear the best armour you can find. He just has to switch armor to hide in shadows (but not to detect illusions).

As to race I rule out dwarf because 18 dex gets you the extra AC and that's what a tank is all about. You'll have plenty of skill points to distribute as Jan will pick up the slack so I wouldn't worry about that too much for race selection. Half-orc is nice, but you get strength items so quickly that it's unecessary. So I'd go with the halfling for the saving throw bonuses (critical for a tank). Gnome is almost as good, but the halfling has better stealth and is harder to poison.

As a pure tank the FMT is probably better. You let Jan and Aerie take the typical mage spells, and concentrate on spells for tanks (the armor spells, mirror image and stoneskin, protection from normal missiles and so on). But I think the F/T is more fun.