Forgotten Tales

I've been grinding keys for a while. Plan is to get all keys before opening doors and chests. So far, I have 1 bright pink key (chest) and 10 door keys (missing red and bright red). This leads to a few questions:

1) do you need to use a bright pink key before the next drops?
2) how many kills have others needed before getting the red and bright red keys? these seem pretty rare (the others dropped "easily")
3) which chests require keys? the yellow "suitcases" or the other ones?

1) You can have multiple Bright Pink Bone Key's in your inventory; having one won't prevent the ogres from dropping more.
2) The next ogre you smite could drop both at once, or it could take 50 kills to get one.
3) If i remember corrctly they all require keys, with the possible exception of one or two chests containing gold(?). Everything you probably care about needs a key.