[Mikuto]

I would assume that if you keep Whispernet off, the battery will last for quite a while, though I couldn't be sure of how many months/years it will last.

I have a 5th generation iPod which I bought right when it was released (in 2006), and the battery still works on that with no trouble, so I figure it would be similar.

As far as the SD card issue, this thing holds 1500 books without one.

Between samples and free books from Gutenberg etc, 1500 is smaller than it seems.