Glad this pack is already getting some use!
Coins, keys, and other items are planned, but will have to wait until later packs (UI/item icon pack). Since I'm going to be focusing on more tilesets and characters for a while yet, I would suggest that you continue to make your own additions for the time being.
I don't plan to add extra animations to the tileset at the moment (like pots breaking or doors opening).
Sorry that I can't help with these suggestions, but don't hesitate to ask for things in the future. I'm keeping a list of additions I want to add (like the levers), and I'm definitely open to ideas!