Are the Mage College room containers safe to store stuff in?
or do they reset destroying goods stored there?

And the same for the Companions hall bed?

In my experience, both are safe.
Though I have not tested any of the barrels, just the wardrobes and cabinets and suchlike.

I have read that college chests are NOT safes, but wardrobes are safe. I think on the UESP wiki.

The companions have a dresser in the community bedroom that is safe and the wardrobe in the hallway there is also safe.

used the college dorm room for a good 20+ hours if not more (didn't use any containers outside of the dorm room, so i don't know about those). barrels and wardrobes were safe. never lost anything. though it was disturbing that j'zargo liked to sit in the chair next to the bed. i wondered if he did that while i slept.

Do NOT use the barrels in the free room you get as an initiate. I returned to level some alchemy and found that my hours worth of mats turned into 3 giant's toes.

Cheers for the advice.
Working on some housing, but need to stash a fast growing library till I get one.
Will risk the wardrobe for now then.

I just wish the companions community bedroom was more .... tidy. http://www.imdb.com/title/tt0077975/quotes?qt=qt0479968, I tell you!