Thanks for this! That’s a lot of useful info.
Your broom-in-the-vacuum-room strategy is a surprise! That’s not supposed to be possible. durp :P
I had a better idea for the vacuum, but too late to implement: It should bind you to the floor, then you can slide left and right, and slide up walls and along ceilings as long as nothing blocks them.
FWIW the whole game is actually possible to beat without using items at all, and there’s a special medal at the end for that. If you really push it for speed, it’s possible to complete in under 2 minutes. Under 1 might be possible, but I haven’t done it.