I have been looking at this story very closely. Right now, from what has been released, I think the answer to 1-5 is “unknown” at this point. As for 6) Neighbors told reporters she was leaving early for work. With DC traffic as it is that sounded plausible to me. People I know go in early and leave at 3:30 or so to miss traffic both ways.
Traffic is not that difficult from SW/SE DC, near the Capitol, to K Street NW.