I suggest a level of arcane trickster replacing one level of factotum. Not having to fiddle with a trap directly is an incredibly good idea. [ edit ] oops. Factotums don't have sneak attack, they can spend points to do an attack like one. I've been playing a mild houserule that expending the points makes you sneak attack as a rogue of your factotum level. [/edit]
I also suggest Magic Sensitive from the Complete Mage or better Vatic Gaze from Player's Handbook II , which grant constant detect magic. Mind you, your DM will probably need you to say "I look at the room carefully with detect magic on" to indicate how you're concentrating on it.
BTW, I just looked at Mystic Backlash in Complete Mage. It's not great for this adventure, but a Sorcerer/Abjurant Champion/Spellsword with Mystic Backlash is fearsomely awesome in a high-magic setting.