Had a feeling about 1 and 4 lol. As for the second challenge, just the vending machine.
As for the item ideas, I had a few of them based on arts n crafts and school subjects.
Like a bottle of glue could be used to temporarily glue a teacher in place to keep them from moving.
A pair of scissors or an eraser could be used to temporarily disable a teacher's attack. (Think of it like cutting/erasing their arms off, just not visually on the models. Could have a sound cue for it instead.)
A beaker bottle filled with a green chemical that could be either super helpful or very dangerous, a luck based item to gamble with. (If it's possible anyway, I was just thinking it could copy an effect of other items or hurt you a bit.)