Hi everyone again!
@Alansplace: thanks for your comment!
@Nyssa: thanks for your comment and for the suggestions, I very much appreciate advices.
Concerning the book cover, the experts on this forum (NiLuJe and Yifan Lu) wrote that it is impossible (it would take some serious modification).
Concerning mixing the new screensavers with the original ones, you can definitely do so! Check out the album Kindle 3 Default Images
on the website. You can pick your favorite images and mix them in with your custom images