Yes thats correct as long as the satelittes are designed to work with the base station.
If they're DECT phones you can have up to six handsets.
Just looking at something basic where they come in a pack of 2 (where one of them rests on a base station).
Yup then that would work where the 2nd phone only needs power. Once its charged - its doesnt even need that because it communicates to the base station all of the time via DECT. It just needs power to charge it.