2. a category can contain any image uploaded to it
3. a gallery is a gallery it does not mean anything more than that. PhotoPost is a community gallery of images
4. same as 3. Albums are personal albums owned by a user. Categories are categories of images an admin defines say dogs cats turtles. Basically broken down categories to post to.
5. The members gallery is a category that displays by user. So users upload to it and instead of a regular category where images would be sorted however the sort is defined it is grouped by user. In any category an admin is the only one who can set a cover.
6. Not true
7. Not sure what you mean by this
An admin sets a category avatar by viewing a photo that exists in any category and sets the index thumb from the photo options menu.