!If you ever forget the prefix do
!prefix? no matter what, that command will display the current prefix on your server so long as Gaius has perms to see the chat and talk in it.
!command ? will display it's quick help message.
Not necessarily. Any discord role with manage server or admin (or owner) can modify the bot's functions. The bot will automatically start attempting to moderate chat for spam, chain-mail and malicious links. Filters can be enabled and disabled via command among other things.