You need Elevator, Rudder and Aileron. (Flaps not necessary)
This thing, flies like a quadcopter up to an altitute using the 4 motors and then we have a transition (either manual or automatic). During the transition, the back motor kicks in, then the controls goes to rudder, elevator and aileron and at the end of the transition the quadcopter motors stop completely. After that it just flies like a plane.
I strongly suggest building a quadcopter with arducopter and fly with it, then building a plane with arducopter and fly with it. You are going to need both knowledge as Quadplane is just both of them with a transition between.