Yeah, if you don't have gauntlets and you're fighting them without a weapon, they damage your arms really badly, even sometimes causing them to be severed off after only a couple hits.
Magic Mushrooms are easily one of if not THE worst creature in the game.. Having a level so full of them that it's impossible to leave, then getting teleported into the dwarven minefield, full of all kinds of shit, and getting killed by an eagle feather golem. Ever since I had that happen I've hate hate hated them forever.
Yeah, the kicking chests against the wall is commonly known. I'm not sure about this one, but I remember an old thread that said that maybe if you kick a door diagonally and set off a trap, you don't take as much damage from the explosion because you aren't directly in front of it?