Anyone can invite anyone they want but if someone in the group has a problem with a different member there is a chance of them being kicked, especially if it’s one of the original members that want to kick.

It’s not possible to become admin, if you are invited by a admin you become a mod, if a mod invites then the member is going to stay a regular member etc.

If you want the bind for the group tag but can’t figure out how to do it you can ask someone who has it and they’ll tell you.