The pictures look OK, but its hard to tell the errors you described in building without some closeups. Regarding CG, since you mention having to spend $200, does this mean you haven't yet mounted the electronic? These MUST be installed in order to check the balance. Mount them as far forward as you can, including getting the battery in the nose under the fuel tank. But keep it accessible in the event you find out you want to move it backword. Most trainers should balance on or near the wing spar. if you're within 1/2" of that, the plane will probably fly fine. Just have an experienced pilot do the maiden flight for you.

Brad