Smoky, welcome to the world of designing. I would like to make a couple observations of your plans so far. I think a symmetrical airfoil is a great idea. Many guys had learned to fly on the original Ugly Stik and the Bridi series of trainers. I would not however incorporate any washout. While inverted it becomes wash in. The tip stall tendency you are trying to eliminate can be done with other techniques such a keeping the weight in check, correct CG placement and the use of aileron differential. Another tip would be to reduce the tip cord just a little for the last 10" of the wing similar to what Bridi did on the Kaos. With today's available servos one per wing surface is not an issue, what could be an issue is flex of the surface. An aileron or flap that will twist easily can flutter. No dihedral is a personal choice but will reduce the airplanes self righting capabilities. That being said, a cabin mounted wing will exhibit some dihedral effect. Your airfoil could be a hot topic all by itself. I have found that unless you are building a pylon racer or a sailplane, the actual curvature of the airfoil is fairly unimportant within the same family ( flat bottom, semi symmetrical and symmetrical ). Where you place the airfoil high point and airfoil thickness does play a part though. For what your goals are, I would go with 14% to 16% airfoil thickness with a high point at 30%. If you are doing a foam core wing you can move the airfoil high point forward 5%, another little trick to avoid tip stalls as well as place a little additional drag out at the tips that will aid in directional stability. Good luck with your project. I hope you will do a build thread.