Yes the O2 housing/Midpipe package includes the downpipe. O2 housing is just another name for downpipe actually. But I don't have it so I can't really comment, but everyone I've heard of buying it seemed to really like it.
No problem, go for it! I almost jumped on it last black Friday but I just don't want to remove the first cat. I want to replace both with high flow so I'm stuck with only the mid pipe. But I love the way it makes the exhaust sound especially with being able to hear the turbo out the exhaust.