Wordpress sites publish an rss feed by default at site.com/rss or site.com/feed, so there’s a good chance a site you want an rss feed for has one even if they didn’t intend to.

They will. My experience community building thus far is that if you can build up one anchor community to the point where people are organically sharing content and commenting, other adjacent communities will start to generate the same sorts of things with smaller subscriber bases because that anchor community is keeping people’s eyes here. Just a question of time.