Close vents in winter?

Trying to put the crawl space together since I've gotten the foundation in and put drainaige tile around perimeter. I now have snow in it and the ground is freezing (northern Wisconsin). I have clumps of frozen ground from the backfill into it and snow on top of that. Is this area suppose to be level and dry before installing vapor barrier? Where does the snow and wet stuff go if I do that now? thanks-you've been very helpful for me so far!

Is there a requirement that non-load bearing walls run all the way to the bottom of the joists? Here is my situation: I am planning to finish my basement. The exterior (poured concrete) walls are 9' high (we paid extra when they built the house). Checking all around the basement, I find that if I install a drop ceiling about 7'10" above the unfinished floor, I can have a flat ceiling - no boxing around ductwork, pipes, etc. What I want to do is to build all the walls 8' high (using metal studs) to minimize cutting. Walls against the foundation I would anchor to the concrete with a 1-2" wood spacer along the top track of the wall (sort of like a horizontal furring strip). This wood strip along with the top metal track would act as a firestop. Is there a fundamental problem with this plan? I notice that the offices at work are framed pretty much in this way, but that is commercial code (vs. residential code).