Originally Posted by carld
Decided to test this. I sent two Amazon books to my Kindle, moved them from my Kindle to my Desktop, added them to Calibre, changed Title and Author and sent them back to my Kindle. In both cases the Metadata changes were preserved. As far as I know both files had DRM, one was a non-self-published freebie and one was a book I purchase just a couple days ago.
the op also asked about a cover change, i don't think that'll work as in my experience a cover change requires a convert to work in the device. did you try a different cover?