The Question and Answer section for The Lion, the Witch and the Wardrobe is a great resource to ask questions, find answers, and discuss the novel.
I tend to lean towards Aslan being a flat character. Aslan is a Christ-figure that posseses a few of Christ's simpler traits. Lewis does not examine Aslan with any complexity.
They decide to rescue Mr. Tumnus.
Edmund meets the White Witch and her dwarf.