At QB I'd sit Fitzpatrick. The other guys have higher floors because of their legs, IMO. They also have better running games right now, which, at least in theory, should open up the passing game a bit more.
I think Thomas is the clear best guy out of your second group. I would also start Jennings. I really don't like Jennings much at all--he looked pretty pedestrian last year in JAX when MJD went down--but hey, he's a starting running back. There are a lot of question marks in this bunch, so your best bet is to chase touches. Jennings will definitely get touches, so throw him out there and see if you get lucky. Lastly, I'd go with Terrance Williams. He posted a solid line last week, and it looks like Miles Austin will again be watching in street clothes this weekend.