What are some good books/authors to read to help increase my vocabulary and writing capabilities?

The best book for you is one that actually engages you and you enjoy. Pick one that you consider intelligently written because you want to improve yourself, and, while you read, write down any word that you want to look up. Try to figure it out in context first, and then look it up. That will improve your vocabulary a lot. That's what I've always done, and I've always had a good vocabulary. I can't tell you what book because it has to really be something that you choose, personally. That's best. Maybe the site Flashlight Worthy can help you find something.