Oops, you used the command in response to the actual HBIT source account (won't work, sorry). Instead, use the command in reply to any other account, such as the official HBIT mine at @hivebits.mine and it will work. :)
Zero. HBIT is different in that way. If you have a Hive account, you can use the ! hivebits command (no space, and it won't work in response to the @hivebits account, @hivebits.mine is recommended).
Greetings. How many coins do you need to keep in your wallet in order to be able to press a command?