Slav - Theory Heavy Book I have come to the realization that studying opening theory is far and away my favorite aspect of chess. 

That being said I am looking for a comprehensive theory heavy book on the Slav. I would like one that deals with pawn structure formations, middle game plans, and potentially end games that occur frequently. I would also like one that deals with the subtleties of move order as sometimes that is glossed over in books that are rushed to be published. Any help would be greatly appreciated.  

Looking for something aimed at the 2000+ level
http://www.amazon.com/Grandmaster-Repertoire-17-Classical-Slav/dp/1907982388

Grandmaster Repertoire 17 by Avrukh is probably what you're looking for. It is extremely dense and detailed. It will require a lot of work to get all the information that you need, but there are a lot of rewards there as well.

If you have not studied that Slav before, I would recommend:

http://www.amazon.com/Slav-Move-Everyman-Chess/dp/185744678X/ref=sr_1_2?s=books&amp;ie=UTF8&amp;qid=1347014456&amp;sr=1-2&amp;keywords=slav+defence

Slav: Move by Move by Lakdawala as it gives a great overview of the plans and ideas of the opening and provides puzzles and quizzes throughout the games to test your understanding.

The Slav is a great opening and I wish you luck in your studies!