Much answers here come from text books and other publications. I think it's a good idea to add the possibility to add (just like tagging works) books to an answer. A lot of people can use these suggestions to read more about the topic/question.
Not happening. Unlike the tag taxonomy that's relatively limited, the number of books is unlimited and the number of books with reuse value across the stackexchange format is also unlimited.
Traditional citations, in the text of answers, is sufficient.