1922
This still baffles me, but I guess it's good for federation?
(i.imgflip.com)
A community dedicated to fediverse news and discussion.
Fediverse is a portmanteau of "federation" and "universe".
Getting started on Fediverse;
Yes (just checked out of curiosity). And Burggit, and Lemmygrad, and Exploding-Heads and virtually everyone else. They don't block other instances, as far as I can tell.
According to their instances list, they do not block anyone, and according to the other search thingy they are only blocked by 7 instances, all private Mastodon instances.