One of my many moribund writing projects is THE MARK TWAIN COOKBOOK, for which I did a fair amount of preliminary research a few years ago. One thing I learned is that A TRAMP ABROAD is probably the best published source of Mark Twain's views on food. The book mentions "breakfast" more than 30 times. Most of the comments are perfunctory, but chapter 49 contains a substantive discussion of the subject.

On the subject of Mark Twain as a teacher, some of his views on that subject are quoted in the NEW YORK TIMES article of March 17, 1901. That article is online at http://twainquotes.com/19010317.html