LessWrong doesn't have this event cross-posting. Possibly it's less relevant for their site than the EA Forum.
Hi and welcome! :) Yes, the weekly socials are open to anyone. If you have specific questions, I recommend contacting the group organizers directly, as they are more likely to respond via email or Facebook.
Sure thing - I just assigned you as an organizer to the group. You should have access to edit the group's info and events.
We have a contractor who cross-posts EA events from Facebook and Meetup. If you'd prefer to manage your group's events yourself, we can ask the contractor to skip your group.
Yeah I think it needs to match a location on Google Maps. I updated the address/location so hopefully it's correct now - you should also be able to edit the event location yourself if it's still wrong.