Add a "close icon" on a google map pop up + Add thumbnail image on Facebook for shared posts

I have a wordpress website ([login to view URL]) and need 2 amendments. 1. I need to add a "close icon" on the map pop up. When users click on a map marker, a window opens with a summary about the place. However, to close it, people need to click on the marker again which is not really intuitive. I would like to have a close icon on the pop up itself. 2. Whenever a post is forwarded on Facebook, the images of the posts are not called. It does not generate any thumbnail. I need to fix this as well.