I could understand if you feel overwhelmed with all of this, so I have a simple suggestion on how to organize everything, if you don't mind.
You could make a thread in this forum notifying the members that there are a few people who feel reading Our Inner Ape would be a great addition to Your Inner Fish, and that it's recommended but completely optional. People could then talk about Frans De Waal's book in that thread in general if they like, and discuss any parts that are relevant (if there are any) to Your Inner Fish in the Chapter threads. Maybe my suggestion sounds more complicated than what you have planned. If that's the case, please disregard this post.
This is going to sound stupid but... I'm curious as to why Saffron and other members feel this book would enhance the discussion on Neil Shubin's book. Is it relevant at all to what Neil Shubin discusses in his book? I guess I'll find out when I check Amazon.
Anyway, I'm going to put Our Inner Ape on hold at the library along with another book I plan on reading. I'm not sure either will be available soon, so I might have to stick to just reading Your Inner Fish on its own.