The Sturdy Birdy does have a fair amount of dihedral. As long as those ply formers fit into the slots in the wing ok, you know you've put it together correctly. Incedently it's the SB II that has ailerons, the original didn't, maybe they added the ailerons to the design without altering the dihedral?

As for flying characteristics? This thing is a brick! Not ideal as a first trainer, but if you've already got some flying experience it's a fun plane to fly; a bit faster than your average balsa trainer....

A couple of other points:

The ground handling is terrible! Make sure you fit a tail wheel, the Dubro will do, just mount it in place of the skid and put the wire through the elevator gap to the rudder. Make sure you hold full up elevator on the take off run until you're almost at flying speed.

Engine: The instructions will have you believe that a 20-30 size is fine. A 25LA barely flies it. A 46LA is the ideal engine for this plane, a BB 40 would be too heavy. Remember there's not a lot of scope for moving stuff around on that channel....