There is now a Readwise plugin published to the Amplenote Plugin directory that provides a streamlined way to synchronize between your Readwise highlights and your Amplenote notebook.
Index of books as seen after synchronizing with the Readwise plugin
As described in the instructions on the plugin's homepage, each synchronized book will keep a list of all highlights made, including any notes that you may have left with the highlight:
Each book will capture each highlight along with applicable links and notes. The note for the book will be tagged with the author's name