http://www.zoly.info/kindle-book-reader/
I’m asking from the point of view of preparing books for sale as e-books. Can different formats be used with Kindle?
No, just see the section “Files Kindle Recognizes” on the official page here for the file formats supported by the Kindle: http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2Fgp%2Fhelp%2Fcustomer%2Fdisplay.html%3Fie%3DUTF8%26nodeId%3D200375630%26ref_%3Dhp%5Fnavbox%5Fk2land%5Ftrans%5Fusb&tag=elec-m-20&linkCode=ur2&camp=1789&creative=390957 Amazon’s Kindle e-book reader
Is the Kindle e-book reader restricted to books sold in the Amazon store?