If I understand right, the on/off switch is not normally needed... just leave it on all the time.

But if I use it to the point where I've exhausted the battery power, I assume that the unit will shut itself off at that point, or will it go into some kind of sleep mode until connected to power?

Thanks. After twenty years of using desktop/laptops and ten years of using Windows CE devices, I'm having to learn to use something different with the n800.