Harry Potter and the Goblet of Fire Theme of Good vs. Evil

When Harry Potter and the Goblet of Fire was released, there was a lot of debate about whether or not it was appropriate for children. The entire Harry Potter series is about a battle of Good vs. Evil, but there's certainly a lot of evil going on in Book 4. The complete lack of concern Voldemort shows when he kills Cedric (whom he calls "the spare") is unsettling for readers of any age group. J.K. Rowling has been very clear that she wants parents to decide for their own children whether Harry Potter is right for them. But she has also stated that she has a moral purpose in showing Voldemort's violence for what it is:

I have an enormous respect or human life. I do not think that you would read either of the deaths in that book [of Frank Bryce and Cedric Diggory] and think, yeah, well, he's gone, off we go. Not at all. I think it's very clear where my sympathies lie. And here we are dealing with someone, I'm dealing with a villain who does hold human life incredibly cheap. That's how it happens: one squeeze of the trigger. Gone. Forever. That's evil. It's a terrible, terrible thing but you're right, I know where I draw the line. Other people will draw the line in a different place and they will disagree with me. (source)

1. In the abstract, it seems that Harry is Good and Voldemort is Evil, but Harry is human and therefore not perfect. What are Harry's bad points? How do his weaknesses manifest themselves in Goblet of Fire?
2. The moral universe of Goblet of Fire is much more complicated than just good people vs. Death Eaters. Which characters best represent the moral grey area of Goblet of Fire? What role do these morally ambiguous characters play in this novel?
3. Morally speaking, which characters in Goblet of Fire most surprise you or defy your expectations?