Regarding Zathura the most readily available resource can be found by running man zathura and man zathurarc. The same info is of course on the web.

It does 2 page view, optionally shows progress, and with the mupdf backend supports epub and pdf and a few more.

Now it doesn't support mobi but calibre can automatically create an epub from the mobi on import.

Calibre is still useful in 17 different ways even if you don't actually use it to read the book.