My girlfriend had a saying that said, in effect, if your teenager doesn't go up to her room screaming "I hate you" at least once a day, you're not doing your job as a mother correctly. But seriously, as a mother of a 14 and a 12 yo, I would in this situation figure out some guidelines ahead of time (like amount of time spent with friends, amount of calls, texts, ims, etc.) and explain them calmly making sure she understands these rules. Don't forbid anything, just let her know what is allowed. Any infractions, and these allowances can be diminished, all the way down to nothing if she keeps up any bad behavior, good behavior and building of trust can be rewarded with more priviledges. Remember YOU are in charge, and I agree with the poster who said DO NOT feel bad about reading her book, I would have done it in a heartbeat!
I don't have all the answers either, but personally, I would, after catching her in lies already, start these allowances low, and have her show you that she can be trusted. Also, TALK TO THE OTHER PARENTS of the friends that she is hanging out with and confirm all plans with them. I've been burned on that one, where they say they are staying at one friends' house, and the other friend says the same thing, so the result is that they are free for the night. Good luck with everything.