Thoughts on re-entering the book blog world

I have really taken my eye off what is happening in the world of book blogging (but not blogging as a whole but that's another story!) so now that I'm back I need to get up to speed!  What have I missed?

Which are the must reads blogs now?
What should I take part in?
Are people still using Blogger or have lots of people gone over to Wordpress?
What's happening about GFC that I keep seeing?
Does everyone have Twitter now?
What about a Facebook page?
What else do I need to know?

I have so many questions and things I want to know! I feel like I'm returning to a friendly world which I have missed but that life made me take a break from.