Good to hear about your progress! I'm waiting eagerly.
About color vs. bw ----
although I am ready to pay 100 USD for the book -- for the marvelous CONTENT! -- , I would be a bit reluctant to do it just for color printing. If the book explained color theory etc. it would be more important, but BW graphics and photos in a book describing mostly BW emulsions would be IMO sufficient. If it is $25 vs $100, If I was you I would make it BW and $35 and use the extra $10 for buying some silver nitrate .
Or to rephrase, I don't want that much money go to the print, but rather I'd support your research efforts with that money.
So, color is a nice extra, but not worth 4x price.
Most of the technical literature of this area is printed in black and white anyway and the photos and illustrations make perfect sense. Shanebrook's book is an exception as it is strongly a photo book.
But, I'll be happy in any decision you make.