As for books, when I buy them on Amazon I select "transfer via USB" which let's me download it and when I add it to Calibre, the DRM is stripped by DEDRM_tools  before transfering into the Kindle.
 Note that the tool only removes the DRM, it doesn't anonymise the file. It's still associated with your account.
I’ve used deDRM a lot in the past, but it doesn’t work with the latest DRM on (I think AWZ3 files) - but perhaps it’s been updated since I last checked about 6 months ago or so.
If I can download a “legacy” file format - I might try that.
Thanks again for your input!