A friend sent me some links to a very nice CliffsNotes-style reference to the essentials of metabolism and related topics.
Reading it all in detail now -- this has got to be, by far, THE most clear, concise and yet comprehensive description of almost everything related to the topic. (And that's not an easy thing to do, given the extreme complexity of it.) Very impressed!
Highly recommended to the mere mortals like myself, who only have tangential knowledge of the subject; hope you enjoy!
http://www.diagnosisdiet.com/food/protein/
http://www.diagnosisdiet.com/food/fats/
http://www.diagnosisdiet.com/food/carbohydrates/