3) Every round you're not in an actual battle, and you don't see any unexpected magic, you do the same thing: Summon an Earth Elemental, send it running along your intended path of travel. If it springs a trap, call a halt, and send the elemental by repeatedly until you know exactly where the traps coming from. Then zap it until it's a puddle. Then send the earth elemental by it repeatedly to make sure it's dead.
Am I the only one who thinks that setting off traps repeatedly, especially in a place like the Tomb of Horrors, is a spectacularly bad idea? There are some traps which have a large enough area of effect that you'll get zapped by it along with the elemental. There are some that will cut off options for advancement or retreat. There are some that will summon or otherwise attract the attention of creatures that can either deal with the elemental plus the wizard, or which are smart enough to recognize what the real threat is, and focus on the wizard first.