RE: Wing incidence degrees for a low wing monoplane?
I can guarantee you that the rubber model will have ended up with some down and right thrust and so should your engine powered one. It's typical on rubber models to not show thrustline offsets since it's understood that adjustments WILL be needed during the trimming phase. Smart rubber modelers will drill the hole for the thrust bearing with some down and right to get a head start on things and avoid large unsightly amounts of packing shims.
Adding on a couple of degrees of down and a couple of degrees of right thrust would be a wise thing to do.