Jim - Good call on the A-20 - I thought it was a solid-nose B-25, but the cockpit is too narrow. Both airplanes had very flat sides and high-mounted wings.
Also you are correct on the B-18 - it was the Martin B-18, not a Boeing.
I don't think #21 is a Jenny - the Jenny had a fairly large, vertically mounted radiator right behind the propeller and the top wing was one continuous piece, not split. Here's a link to a good shot of a Jenny's front end:
Jenny