Some random thoughts on Facebook and book marketing:
1) Advertising books on Facebook doesn't work. No, I haven't tried it, but this guy has, and his data are convincing to me.
2) 'Like' pages on Facebook are worthless. I've had several writer friends nuke their personal Facebook page and switch to a 'like' page. And that was the last I saw of them on Facebook. I've 'liked' hundreds of pages, but let's see how long it takes to get to a post from one of them in my feed. I'll go count now.... Sixty! You have to go down 60 places in my feed to get the first story from a 'like' page. I almost never read my feed that deeply, so I never see any 'like' pages. And that's not even one of the writer-type 'like' pages. It's the volcano one, which is large and very active. It used to be that you needed 'like' pages due to the 5,000 friend limit on Facebook, but now anyone can subscribe to your personal page updates, circumventing the limit. There's no reason to build a 'like' page anymore. Just clean out any personal stuff on your own page (you shouldn't post anything personal on Facebook anyway, it's not secure) and use that for keeping in touch with your fans.
3) When Facebook suggests friends for you, here's how I figure out if people are open to connecting. I look at their profile--if it's set completely open, it's probably someone like me who is using Facebook to network, so I send them a friend request. If most of their information is hidden, I figure they're using Facebook for some other purpose, and I don't send a request. Once you get above 500-600 friends, you'll start getting plenty of requests and your account will grow without you having to do much. I generally friend everyone, and promptly unfriend anyone who posts obnoxious stuff on my wall.
4) Make sure your profile is set to be open and searchable. You want people to find you, right? If there's anything on there you don't want everyone to see, delete it.
5) I block all games and most apps. That keeps my feed clean. Most of the games seem to reward you if you invite others to play, but I'm not on Facebook to make money for Zynga--I'm there to stay connected with fans, librarians and fellow writers.
6) Google+ is a strange hybrid of Facebook and Twitter. Honestly, I've had a tough time getting people very engaged there, so I'm not the best one to talk about what works. You should probably create a profile, particularly since your Google+ profile will often be the first thing in search results for you. Beyond that, if you like it, great, but I'm not fully sold.
Hope that's helpful. What did I miss? Let me know in the comments and I'll edit this post or add another. Thanks!