I just beat the questline, and own it, but Im still afraid of putting anything in any chest. Do they respawn or no? And can I leave random things around? I wanna decorate the floor with skulls.

I beat it as dawnguard and looted the castle then went back a week later and found everything respawned from blood potions to bone hawk ring and amulet in display cases

Damn...that svcks... The blood potions are useful though but blah, I wanted to throw skulls and daedra hearts everywhere