Originally Posted by elmussol
Now I'm getting a little further in, I'm developing strategies for my library management. In all likelihood the majority of my epubs are not going to be coming from the Kobo store, so this needs to be conisdered. Note that I have at this stage not downloaded anything from the Kobo store.
Poking around in the file system I find that I have on the Kobo's internal memory:
full of zip files of the preinstalled books. I assume these are restored (with the software images) on factory reset. If I copy these to my hard disk, where calibre library resides so I can do things like tagging them, the zip files are copied directly. If I then view this copy, I get the garbage I would expect from an unzipped file. Do I need to explicitly unzip them for calibre's use?
At any rate all these books are available from Project Gutenberg, so as far as I can see I lose nothing by deleting these from the Kobo's internal memory and being able to manipulate the metadata in the normal way. Am I missing something important?
Those books will be kepubs, not standard epubs. kepubs are Kobo's modification of epubs. Purchased kepubs have DRM which is different from what ADE uses. Some free kepubs don't have DRM. If there isn't any DRM, the calibre viewer can open the kepub as an epub. I haven't seen any problems the few times I have done this.
From what you say, I think the books are compressed and need to be uncompressed to open them. But, they might be tarred or gzipped rather than zipped. Try opening them with 7Zip.