Is there anything I need to sign? I know some clubs have liability forms and such.
Please re-read meetup.com's terms of service, especially section 6. You agreed to it in order to use this site. You may not have read it, but you had to check the box that said you did. In general, section 6 says if an organizer or any member places a event on the calendar and you get injured or something at it, it's your own fault. If you can't live with that, this group isn't for you.
Who runs this group?
This is a group of people who like to climb indoors and outdoors. There is no one in charge. If someone starts telling you what to do and you don't agree with it, don't do it. Use your own common sense and leave the event if you think it is too risky for your taste.
So who is this Lilly who is the organizer? Isn't she in charge?
Lilly runs the web site. She can post calendar entries and moderate the message board, as can the other organizers. (Moderate means if someone puts something up that is inappropriate, she can delete it.) Some say she is the leader, but I think she is more of a cat herder. If you have ever tried to tell cats where to go, you will understand that.
What are the rules?
If you want a group that has rules, you don't want this group. Ok .. there is one rule, and that is to be safe. That means if someone does something you think is unsafe, don't climb with them. If that isn't good enough, tell them about your concerns directly or whoever organized the event that you are uncomfortable. Or email the organizers. Nothing may get done about it, so be prepared for that. No one forced you to go to an event, and no one will force you to stay on one. You can leave at any time.