It seems i'll have to learn mySQL after all:)
When you said "post state" do you mean hiveDB will tell me if a post was edited or not? That would be useful because sometimes get_content doesn't show this info, even the post was edited.
How much delay hiveDB has compared to the head block?
No, for the post history you would still have to query sbds or SteemData Mongo, and compare the diffs between posts with the matching author/permlink.