Harry Potter and the Sorcerer's Stone Theme of Courage

Courage is one of the hallmarks of Gryffindor house, and it's also a defining characteristic for our main characters. Harry, Ron, Hermione, and even Neville all reveal themselves as possessing outstanding bravery, and it's their courage that helps them get through the climactic ordeals at the book's end. As Dumbledore praises them at the year-end banquet, he honors their explicit and implicit courage. This shows that the Hogwarts faculty values virtues like courage and loyalty as much as they do more wacky branches of magical education. Being able to make feathers float is all very well and good, but when push comes to shove, what really matters is how you face your fears.

1. If courage goes so far towards defining Gryffindors, is there anyone who acts so courageously that he/she ought to be a Gryffindor? Is there anyone who doesn't?
2. Is it braver to stand up to your friends, as Neville does, or to stand up to He-Who-Must-Not-Be-Named? Why?
3. How does this book define courage? What is the most courageous act of the book?
4. How can Harry's promise to no longer look into the Mirror of Erised be seen as a courageous act?