What did you end up with?
I am considering a very similar build if not the exact same, for almost the same use case, so I'm interested.
About H670 vs Q670 I can tell you what I read elsewhere, that their only difference is the inclusion/lack of intel's vpro remote access. Which might be useless for many. I also read that this feature only works with cpu's of (or above) the 500 range - eg. 12500, 13500, 14500 etc, and not with cpu's lower than that, but I only read this in one place which I cannot now remember.