On version 0.19 you can block instances so that you don’t see any posts from that instance, instead of having to block communities one by one, you still see comments from users of that instance in other posts so it isn’t completely blocking the instance.
None. I wish I could see more content. Not enough is made of the fact that you only see content your instance is already connected to. Part of my frustration with the platform is that I joined a neutral instance to have as much content as possible, but relatively little of it is shuffled to me in the all feed. I like discovering new things online. I hate the catch 22 of federation content access, where being on a large enough instance to be certain you’re well connected means being on an instance that has blocked a lot of content to appease its larger userbase.