[Ripplinger]

If all you're doing is settings tags as you want and the publication date to the original date of the paper version, instead of the date the ebook was published, that's easily done in Calibre through the Edit Metadata option. That's Calibre's metadata files.

As far as I know that information is not within the epub itself in any of the files. That extra info is always downloaded from other sources such as Amazon, Goodreads, etc.

And for myself, when the reader has 1.4GB space left after the OS, yes, I care if books are overly bloated for no reason. Don't get me wrong... I'd never delete maps, etc. as you say are sometimes included. I will compress them though when I see they're 500kb in size for each image when you compress them to under 100kb each or more. But really, the identical image for the top of a chapter... you don't need a different image file for each chapter. That's just wasting space stupidly. That I won't do.