@aschrijver Thanks for your question! The IRC room can be accessed in your browser at irc.w3.org/?channels=social We use it to take notes during the meeting, which are then automatically published to w3c servers. We also use it for queuing, because there is a handy bot that can manage that for us. But if you can’t or prefer not to join the IRC, you can fall back on ‘raise hand’ in jitsi to queue. It is easier for the chair if everyone is using the same mechanism, but we manage if it’s not possible.
The rest of the meeting joining information are published on the announcement for the specific meeting.
It is preferable to join the socialcg but not required. The main advantage we get from this is upon joining you sign an IPR agreement through w3c that appropriately licenses any substantive contributions you make to the groups work. (This basically means if the group produces an open standard with your contributions, you/your company can’t later sue anyone who implements it for copyright infringement - it protects everyone involved and ensures the standard is truly open.) Since we are not working directly on any technical specifications as a group at the moment, this is not particularly urgent. It’s also okay for observers to come to meetings and listen. It’s just as soon as anyone has a significant contribution to make to technical that joining becomes important.