There was a deliberate space in the link due to my then low post count. Anyway. As far as grades go, I'm not really sure. It's basically whether or not I make it to the conference (I got approved yesterday). I have plenty of wings to complete the project, I just wanted to see if anyone wanted me to test anything for them and also I have a bit of spare time and I'm always looking for cool ideas. It is a high school senior project. I'm 18 BTW.
I've already had a few weird things happen that I don't really know how to explain. It's not a big deal. I think it's pretty cool actually.
So as far as I understand, the reason why wings are twisted (basically different angle of attack on the sides vs the center or different airfoil) is because the air coming off the roof is flowing differently than the wing coming around the sides of the roof. This is because different wind characteristics make airfoils stall at different angles. Generally you want the most angle of attack without stalling the wing. You can learn more here
(funny coincidence: the guy in this video is one of my mentors). With the NASCAR spoiler, I imagine that that is partially due to aerodynamics and partially due to visibility. Or if you recall that Ferrari FXX, really the place you need the downforce is on the sides (ie where the rear tires are) so the middle section is less important.
I have considered doing twisted wings and anhidrel/dihedral wings but that's only very recently. Basically every wing (aside from a few) have been sort of variations on that NASCAR spoiler you posted or flat drag style wings.