This is so funny! I always assumed Daph's parents had more money, too! I guess it was subconsciously because of the car! Or because of her amazing and elaborate wardrobe!
I always assumed it was a sorority house! But you are so right about her not being a sorority girl and we know she doesn't live in a sorority later, so. Yeah, it was her parents. That means Justin had sex in Daphne's parents' house! Possibly Daphne's bed...well, at least that would explain why he was so comfortable telling the people at the door to fuck off.