I'm leaning towards Objective C I think, since I've had some (limited) exposure to it. I know I want to learn C sometime, but I guess its not necessary right now. I'm wondering if anyone knows of any good 2d OpenGL tutorials. The Red Book seems rather 3D oriented, but I just want 2D. As for Unity, I'm not exactly looking to spend $200 for a game engine. I'll go for a programming book, but there are plenty of free things available that would work fine.

Well, if you know Objective-C, you know C since it's based entirely on C.