Love v. Kwitny, Twin Peaks v. Publications Int’l, Ltd., Warner Bros. Entertainment, Inc. v. RDR Books, (and check out Castle Rock Entertainment, Inc. v. Carol Publ. Group), all of which are summarized at our Stanford fair use post. (You also cite Cambridge University Press v. Georgia State University, which is currently on appeal at the 11th Circuit.) One common thread through many of these lawsuits is whether the infringing work used too much of the copyrighted work. When too much is taken the use is no longer "fair" because judges believe that the consumer is buying the infringing work for what it takes, not what it adds.
How much is too much? We don't know how much you've taken, but that will likely be the key issue (not whether you are a nonprofit, or whether Don Juan is fact or fiction). When measuring "how much is too much?" judges sometimes look to the total number of words taken, or sometimes they look to the percentage taken (the court in Cambridge University Press proposed an educational fair use standard of 10% from a 10 chapter book). In other cases, quality of the quotes, not quantity is what matters (that is, did you take the "key" quotes that comprise the heart of Castaneda's works?). At the same time, other factors, especially your educational purpose weighs in your favor. Having a transformative purpose helps but keep in mind the defendant in Warner Bros. Entertainment, Inc. v. RDR Books had a transformative purpose but still lost his battle over using Harry Potter.
Is it fair use? We can't tell you. A copyright attorney, after viewing your work, may provide you with a fair use opinion but unfortunately the only person who can tell you for sure is a judge ruling in a lawsuit ... always an expensive proposition. Of course, this will only be an issue if somebody is enforcing Castaneda's rights, that party sees your work and can afford to pursue you.