2) I like my main character to be a warrior, but with the Death Knight in the party using the main as a warrior is a waste of time - DK seems much much better at it...
Well I'll have my main character a Fighter and the DK a Wizard, as I like being a fighter.
Oh and some interesting info on this topic from ForkTong (Larian)
So wouldn't it be logical to make him a wizard with high armour and resistance levels? That way, the armour you pick up, mostly with strength requirements, which cannot be worn by him anyway, can benefit the hero character, which you would make a warrior as to meet the STR req's... If you want to go for a wizard/warrior pair, of course.