The idea behind using differential in ailerons is that the deflection of the control surface causes drag. If you reduce the deflection on the outside wing the plane will tend to pull toward the direction of the turn. The aileron on the outside wing goes down in a turn. Regardless of whether it is a shoulder wing or low wing, you want more up than down on both ailerons.

As for flaps, I wouldn't suggest using them for racing. Flaps are designed to slow the plane down. If your plane is creeping into the pylon on turns it is a often sign that the plane is nose heavy requiring extra up trim to fly level. Once the plane is turned on it's side, that extra up trim cause the plane to pull into the pylon.

Blessings, Terry