When I buy kindle books they automatically go to 3 places - my Kindle Paperwhite, my iPad mini and to another tablet. If I delete the books from the iPad will this delete them from the other places as well? I'd hate to lose everything, but my iPad needs a good clean out and I'm trying to find ways to do this.
When you buy a Kindle book, it's stored in your Amazon account. A copy also gets downloaded to whichever device you bought it from, or whichever device was selected in the 'Deliver to' menu if purchased from the website.
The book does not automatically download to all of your other devices - the cover or title just gets displayed on the 'All' or 'Cloud' list and can be downloaded by tapping on it. If you switch to the 'Downloaded' or 'On Device' view, you'll see only those books that are actually on that device.
To remove a downloaded book from a touch screen device, hold your finger on the book for a moment (long press), then tap the remove from device option. The local, downloaded copy will be removed from that device only. The book will remain in your account and on any other devices.