The switch on the right will only be set to Return To Home if you set it that way. The default is ATT Mode for the center and bottom position. There is also a setting for how RTH works - pick Return and Land.
Yes, it will RTH automatically if it loses the signal, including if you turn off the controller. If set, setting the right switch to the bottom position will do the same thing. You can set the right switch to ATT mode (after turning the transmitter on if it is off, of course) to regain control of the quad. In that case, you would want to push the right stick away from you. The quad turns to face home position before it starts back, so pressing the stick away from you causes the quad to move forward (toward you). Just make sure you give it time to pause in hover, turn and start back before you do this.
You may want to do this, especially if your battery is getting low, because the quad can move much faster in ATT mode than it does in RTH mode.