As far as I know you cannot currently

No passwords per room yet

in settings

I don't know but it's probably called "beekeeper" or something.

nostr:npub1sdu2jqurplu9cpkqx6gnkp4hxtllg52z9vnw26f0nchp5h3urv3q7sje9m is correct. This will also make the room private and it wont be shown on the main page.

Another option is to set a lobby. If you are expecting a larger group you can use this function. It allows you to see who is joining and lets you choose who you would like to enter.

If you need any help or just want a test run of the site for some tips and tricks feel free to contact nostr:npub1mu9wmykl7qx5llk69axd3rvk0hzhdd25jsqtj2hmnzjpn2sxum6s8jjj0t

Pic related to first response