I came to the conclusion that I should leave Facebook quite a while ago now. However, almost all of my friends have and constantly use Facebook, and it remains almost their sole method of contacting me. My friend group and I are all around 16, so that likely explains things.
I've been using Facebook chat via bitlbee (which uses Jabber/XMPP) for several months. It was supposed to stop working on April 30th, but for some reason it does still work.
When someone compromises your system, you can't know everything that has been done. The only truly safe thing to do is reinstall everything from scratch, backing up configs of course.
Maybe China are trying a new approach to censorship. Instead of blocking things themselves, perhaps they're trying to get sysadmins to block all of China. I imagine it would save them a lot of work.