1-The lockbox key opens to the electrical box int he side hallway at the very beginning. We don't have anything for the security box yet.
2-The artist was just adding a phone number and didn't think anything of it. Now that you pointed it out I kinda wanna make it mean something, but I don't think most people would notice it.
3-Not much for the greenhouse yet except for the poster. The Dryad hasn't made an appearance yet but that area will be for her.
4-That the lingerie shop key. You used it in the very beginning.
5-Initaly I wanted to add a small toy character. Thought that could be fun, but the Lead has filled the roster out quite a bit already so that became low priority. Currently there no way to get the toy out but we haven't forgotten about it.
6-That's a file from v0.16. Sometimes it's easier to reverse engineer the free release when I change one of the systems such as the gallery. There is no way to reach that in the free version.