rear fog light is for they really foggy days, say if you can just see the car up ahead that is only 20meters or so infront, well then i guess the car behind you can just see you too.
fog light is really bright, and being red they will know that there is a car infront and thats your car they can now see.
little switch is for the wiper arm, if you have snow on your wiper arms, thick snow, that basically heats up, melts the snow around the arm to allow it to move much easier.