I think this should be database version rather than API version given that most features (or bugs, but I like to stay positive) will be tracked with the database rather than API version other than, say, “oh, the API works like this starting at database version x.y (well, if you are using API version XY0 or newer)”. But everything else I don’t think should depend on the API version.
I do think that prefixes for categories is probably overkill, unless there are overloaded terms, but I can’t think of any off of the top of my head. (Maybe golang instead of go?)