The Kadet is a wonderful plane to learn on. 2 stroke again is my vote, and making a two piece wing. Many ARFs are joined by the attaching wing bolts these days, I wouldn't hesitate to do as RBACONS suggest, but going in 3 ribs wouldn't be absolutely necessary, but shear webbing often is what I do for most of my builds whether the plans call for it or not, near center. If anything I scratch my head when I run into a kit that doesn't suggest shear webbing in the plan. The strength increases dramatically locking in the spars that way.