I'll put in a vote for speeding things up. The first two chapters are just illustrative stories based on actual cases. A way to get the reader interested. The real meat of the book begins in the later chapters. Given the current pace, we may be taking weeks for each of the later chapters.
I suggest using the role model of CatsPajamas posts for 12 Step Study of Alanon. She posted the step, then she posted commentary. Next Step, then commentary. Memembers can join in at anytime. The original group may be on Step 3, but a new member can pull up the thread for Step 1 and start at their own pace. As long as the threads do not get locked down, they can be commented on at any time.
Using her (Cats) model again, A chapter a day could be posted. I like how you posted the followup questions early in the thread. I suggest posting the Chapter Title, then a post about the follow-up questions to give the reader a study guide.
In 3D, a book club must stick to a schedule or the readers get lost. In cyber time, we can post the topic Chapter and members can join at anytime and take it at their own pace.