The Second Read Through

I'm finally starting Harry Potter 6 again! Harry and Dumbledore just reached the Dursleys and Dumbledore is talking to Harry in the broom cupboard. Why is the closet outside the house? It just seems odd to me. Well, on this read through I have a mission. I want to see what is happening with Draco and with Snape. How long do we have to wait out to learn the truth behind him????