Can the device function in a "flight mode" - that is with the mobile network switched off, so that I can use it on the airplane or when I want to be "offline" in the evening and just enjoy a good book?

The first pocket eReader

Can the device function in a "flight mode" - that is with the mobile network switched off, so that I can use it on the airplane or when I want to be "offline" in the evening and just enjoy a good book?

Yes, the modes can be selected by a short push on the on/off switch.