Aww, this was such a sweet story! :-) And what a pairing! A boy who's lived in the most Muggle-ish family imaginable and a witch who's too odd even for magical standards. I just loved their exchanges, Luna being so interested in Muggle homes and the PlayStation. Your Luna was just so cute and very much in character; I could imagine Evanna speaking the words.
I think it would be sweet if Dudley helped rebuild Hogwarts. Sometimes, all you really need is that muscle strength. And the whole imagery of Hogwarts being rebuilt by magical folk and Muggles (and House Elves and others) is a great a symbol of people from different walks of life being united as they bring back the glorious school. Okay, I'm blabbering now. XD