Hi there @marksibly. Your link is to the published html page. The actual wiki post is pinned to the top of this forum at this link: Guide for new ActivityPub implementers
At the bottom of the top post in that thread is the ‘Edit’ action for the wiki. Currently there’s no process in place, and you can directly fix any typo’s you found and then save a new revision of the wiki that way.
Yes, but there are so many more different sites and initiatives out there in the Grassroots Fediverse than what is listed there. Projects that are on Software may get some distinguishing template and/or features, e.g. like Discourse ActivityPub integration on that category.