I think we added 3 or 4, not sure.
There's an achievement that tells you that you did the main things, but it's not a 100% thing strictly speaking. You'll be able to track how close you're to 100%'ing the expansion by different means, though. There's a set of loot drops you unlock, which will surely get added to the wiki, and when you get them all you can be sure you did everything there is to do.