After reading your post I've come to a couple of conclusions:
A. You should have advised Seabrook
B. You should write your own Bowie in Berlin book.
I think you have many points that would make a book like that very interesting and not just a run of the mill rock-n-roll book.
I like the idea of interviewing various people from that time and place and even interviewing people of the modern circle like Gail Ann Dorsey. To get a sense of what it means to him now to have been in Berlin is to see the overall affect on him.
I think Seabrook meant well but it would have been better if he actually went to Berlin and got some facts about the locale as you mentioned. Have you read the 33 1/3 book about Low? How does that compare?
Thanks for the review and I can't wait for your book!