I see that KDP can publish 8.27 x 11.69, which I think would work for a book on self defense I’m thinking about putting together. It also looks like photos and drawings are allowed too. Has anyone here published something similar? Any advice?
You can't really change photos to line art. You need an illustrator if you want it to look right.
KDP Print can produce color interiors as well, but color printing is quite a bit more expensive than black & white, and isn't generally profitable in the world of POD (although IngramSpark offers 3 levels of color printing, and I think two of them are lower cost than KDP Print's color printing).
I pubbed a print color book with Amazon (CreateSpace)--a biography of my aunt, who was a marine during WWII. It came out fine, with all the color images properly embedded and all that. But that project was never meant to be a commercial proposition. It sold its expected fifty copies to family members and no more.
Is there some reason why you're not formatting for ebook? These come with color illustrations for no extra cost, and unless you're selling heavily at cons and book fairs, your ebook sales are likely to far outstrip your print sales. Just a thought.
I believe the market for this book will be martial art instructors - many of which are not overly technical and may have an aversion to the ebook format. Also, the size of the book may cause formatting issues when it's reduced to fit the kindle format and images would become impossible to see clearly.
This will be a very small market - particularly to instructors of Tae Kwon Do, a Korean martial art which is now an Olympic Sport. The issue this book hopes to alleviate is that with the inclusion of TKD into the Olympic Games is that the self defense aspect of the art is being forgotten; many younger instructors know nothing about it.