1. If you don't care about reading insights, use Calibre to transfer them. Otherwise upload via
https://www.amazon.com/sendtokindle.
2. Install KFX-Output plugin. When you edit metadata for your books it's best to also have the amazon-id / ASIN for each book. This'll enable goodreads integration for your books. Make sure that
https://www.amazon.com/Kindle-Previe...de=21381691011 is installed on your machine, otherwise KFX-Output won't work. Now you can transfer your epubs to your Kindle in KFX-format.