RE: Roll and pitch coupling
I fly with the mix on at all times.
Use a P Mix for Rudd-Ail and Rudd-Elev
Start with a linear curve and work your way up to a curve mix. IE when the airplane is slower and you need more diflection, the mix required is greater.
Take it one step at a time and don't rush it.
Remember Practice doesn't make perfect, Perfect Practice makes Perfect.
Mark Leseberg Jr.