Hi,
Usually you do not need to create any tables, they will be auto created if the mysql user has permissions to create tables, that is also true for the phonebook.
The plugins page will check the online repositories to list the available ones, so you should allow outbound http access for it to show properly, do you have that enabled in your server?
As for the buttons, if you see your own but not others, it seems to me that you have empty groups or configured groups and assigned them to that particular user, the best way to try is to edit the user and NOT select any groups at all (that means, no restrictions), and go from there.
Best regards,