How might I transfer Kindle books to iBooks?

Yes, just download the Kindle app, sign in and you should be good to go. It will also sync any highlighting and notes plus take you to your place in a book.

Except reading outside in the sun, I prefer using the Kindle app on the Mini to the Kindle device.

I have either the same problem or a very similar problem. I have several books that i've either read or am waiting to read on my Kindle.

I downloaded the Kindle app to my iPad and all the book covers show up. However, when I click on any of them, a blue gas gauge appears with the bar running from left to right. When the download is completed, if I click on the book, I get the following message...

Error

Please remove the book from your device and redownload it from your cloud items. If problem persists, try to DEregister your application and register again.

I should note that all my book titles only appear when Cloud is selected in my Kindle app. I don't remember setting up my cloud account to store my books. Is this a Amazon cloud storage area? Re the error message, what device am I supposed to remove the book from (ipad or Kindle). What does it mean by deregister? I have removed the Kindle app from my iPad and then downloaded it again to no avail.

And yes, I can still read all my books with my actual Kindle device.

As far as I know, downloading the kindle app and signing in should get you access to your books.