And, what's the difference between 部屋 and plain old 室?
Simple! 'heya' (部屋) is an average house-type room.
Anything else with a 'shitsu' (室) suffix refers to a specialized room.
Fortunately, 'heya' is usually spelled with hiragana anyways. But still. . .
Get your SHIT out of my room! Jesus!
You can't wear the crown until you get to the throne room.
You go to a mortuary store to buy a CORPSE,
but you wear a CROWN in the throne room.