1. Apple's Pages program makes gorgeous epub files, which are the industry default. The Kindle uses azw files, Amazon's proprietary format for the Kindle, but they say you can upload epubs to be converted to azw. Elsewhere, they say that html and doc files work best, which is more true than you might imagine. They should simply say, "Sure, you could upload epubs—if you want your Kindle book to look like shite."
The solution: If you're not comfortable hand-coding html, submit Kindle books as docs.
2. When you upload a corrected file to KDP, you have to wait about 24 hours for it to be published. When you download it to see if it converted okay, you'll find it looks exactly like the previous fubar version. You will curse the gods and frighten your cats. And then, when you dig deeply within the KDP info dump, you'll find this:
At this time, it’s not possible for publishers to receive the updated file without contacting KDP Support for help. We’re working to automate this feature and appreciate your understanding with our existing solution to manually send the updated content to your device.The fast solution: Download the Kindle program for your computer, create a new Amazon account, and buy your books again.
We request your explicit permission, and will do the same for any customers who contact us to receive the updated content, prior to sending the revised file because the new version will not have previously saved Highlights, Last Page Read, Bookmarks, and the location of notes may not match. If this is acceptable, please email email@example.com confirming your permission and which title/s you’d like to have re-sent. Thank you.
Note: Customers who purchased the old content can also contact our Customer Service department to have the new file delivered.