1. Calibre: I know it but I only use it to convert ebooks, not for managing my library, so I don't know what you mean exactly. As you know, the E930 is not specifically listed as one of the devices in Calibre. However, since both the device memory and the SD card are accessible under Windows, I assume you can create your Calibre folder on your E930. I think that's what you mean by "managing your library".
2. Epub support: I only had time to test the first epub (Accessible epub3) from the site you linked. I opened them in Calibre and also on the E930, and compared the results. My findings:
- Calibre shows 205 pages, E930 shows 254. I suspect this is due to different font sizes. Interestingly though, the E930 skips page numbers as you advance through the book - the text is continuous though, so no pages are actually skipped.
- Links cannot be opened on the E930, either external or interal (TOC links).
- Dictionary is not supported. There is a built-in dictionary, but it is a stand-alone application
- Text search is conspicuous by its absence
- Text reflow seems to be fine
- What you can do from the menu:
- Jump to any page in the book
- Change the font (8 options)*
- Change the line spacing (9 options)*
- Change the margin size (3 options)*
- Change the frequency of full page refresh (6 options from 1 to 10 pages)
- Change the orientation (Vertical/Horizontal)
- Add bookmarks
- List bookmarks, go to a bookmark.
*There is an instant preview for these settings.
I hope this helps! Let me know if you have any other (specific) questions.