There will probably be several options for an electrical source to serve a new outlet. For instance, it is likely there are several suitable wall receptacles in any given room to extend the circuit to another room or another floor of the house.
In the center of each plate notch, cut a second, 3/4 inch notch for the cable. Make the depth about 1/2 inch to accept the cable thickness, but keep the entire notch depth to a maximum of 7/8 inch for load-bearing 2x4 studs and 1-7/16 inches for non load-bearing studs.
Mark and cut a hole about 4 inches wide in the wall to expose the top plate and a few inches of the wall cavity. Also cut a few inches into the ceiling to allow for reaching in to grab the fish tape.
There are 3 basic types of wall switches you will encounter in most situations. A single-pole switch is the most common you will find and can be identified by two screw terminals, and in the case of new devices, a third one for ground.