I used to read some documents/pictures such as comics or manga. The writing is very small so I need to zoom a little bit to be able to read but when I get the next page the zoom goes back to "most appropriate" size. So, It will be great if eog can keep the zoom level for the current session as well. (I don't want that as the default behavior but if you can add a menu item "Keep zoom level for the session") 

Can you add a shortcut such as "ctrl +  wheelmousebutton" to go to the next/previous document. Actually, the wheel mouse button control the zoom level; I think it will be useful to take more advantages of this hardware so widespread.