Streamer Mode and Online Features

I have a quick question, my friend is a streamer and I mod for them, we were wondering what streamer mode is and what it does. I’ve heard it has to do with the music but we were not sure. Also, if it’s possible to have a lobby with an access code for people to join instead of sending invites to everyone who wants to play.

Another thought was the ability to keep people in the convoy as ghosts only so we don’t get trolls blocking certain jumps to boards or speed traps, spinning people out.