Digital quantized information and analog is just information. Like the letter "i" on your screen is digital and made up of a few pixels= quantized. The letter "i" drawn on a piece of paper is not...
The meter movement has a current flowing through a coil. That coil is on a magnet. The electromagnet with the needle moves according to the current flow. That flow is established by resistive ladders...
No, an input device is something that carries data into something. In this case, the processor. This incoming information doesn't have to be analog information coming from a human, but it sometimes...