How relevant are the Amazon sales reports for your book?
Amazon offers sales reports from Kindle Publishing Direct, royalty reports from Create Space for print-on-demand, and you have sales and author ranks from Author Central.
Why the new pay-per-page Amazon system means more money for me
The entire pay-per-page drama is about the fact that Amazon sells your books also by page and pays more for this than what you get paid for the normal sale of a book.
Kindle MatchBook program by Amazon
Of course I chose to give the Kindle edition for free!