Use your range to take him out. Even when he's enraged, he won't go on the traps, so stay where you are and use your wands/throwables. You will end up taking damage from 2 traps, but it's no big deal, you got the hp for it.
Yeah, I would probably use a fear stone if I had one. Going back and using a fadeleaf would be a cheaper option but might result in jumping from the fire and into the frying pan.
Uhmm... Not. That gnoll is waiting for me. Pay attention to the text "You return to floor 12 of the dungeon".
I used an Aqua Brew to fill the traps with water, destroy them, then fought the gnoll. (I created these Aqua Brews as a way to deal with fiery enemies, like Fire Elementals).