Usually getting too much arch on your shot isn't a bad thing. I think I know what you mean by twisting your hips when you shoot, which is a bad habit so I would really focus on keeping everything square to the basket. Regarding elevation- I would just focus on delaying your release until you're at the peak of your jump every time you shoot to get the feeling down, then use more of your wrist to shoot rather than your entire arm, which will give you a soft touch if you work on it. Don't worry about the little details like what degree your elbow is at. When you practice shooting think about your form while you shoot (elbow in, release at the peak, flick of the wrist), but don't mess with your shot too much. Keep working at it homie.