I'm glad you liked it; I liked yours, too! And yes, I do think when Dumbledore speaks of choices, he must mean moral choices. Sometimes, when reading these books, I think it's a pity Harry has had so little example and nurture to show him what a moral choice actually is. The only people offering him any real guidance, I think, are Hermione and Severus.

Of course, you're right when you say it's very problematic that Voldemort is a raging psychopath. It's a problem on several levels - as you say, it makes him an uninteresting character, but it also fudges the moral message Rowling apparently intends to send. For her preaching on free will to make sense, we must simply leave Riddle out of the equation, as it were, and concentrate on the actual human characters, particularly Harry and Severus. They are the ones who can make choices. Voldemort can't; it's beyond his ability, IMHO.