I can't answer the advertising questions, but I wanted to mention that, as a customer, I wouldn't spend more for a fixed layout vs reflowable of the same book... If I even noticed there were different versions...
What I would be seriously upset about is if I found out that my reflowable version had inferior image sizes compared to a fixed version. I would probably return the book and ask for my money back. How do you know if I'm reading your reflowable book on my phone or on my 12K uber-iThing??
As I mentioned in a previous post, you don't need to worry about image size. Most devices/apps have the ability to zoom/pan on images if they are natively larger than the display size. (try double-tapping on the image??)
If you
reallllly want the customer to see your images in all their glory then link them to your website...
