RE: Biplane Wing Incidence
My Kyosho PT-17 Stearman has -2 in upper win, 0 in bottom wing and 0 in stabilisator. These wings are lifting profile (semisymetric profile).
If the plane are stalling, then upper wing will take over and keep lift while the bottom wing are in stall. Near same as monoplan with wash-out.
Jens Eirik