Wings and fuselage have been merged now, servos and control surfaces linkage are installed. I replaced my own IMU code by a implementation from Sebastian Madgwick he developed during his PhD. His C# implementation is significant faster than my implementation and much more accurate too, especially for low update rates. Simple PID controllers are used to calculate the control surface angles.
More information to Sebastian Madgwicks implementation you can find on: www.x-io.co.uk