(Yes, this should be done by inspecting the document class, but I do not see myself up to the task yet.)
1) What is a straightforward method to incorporate Tufte-book-class-like margin notes to a standard book class?
2) Even though I like tweaking a lot, is it more advisable to take Tufte class as my base, and start tweaking that? (I ask because the class may not be trivial to tweak.)