Cost of digging out a basement

I have a 3 foot high crawlspace under part of my house and it has only a dirt floor. I guess I'm just assuming this is a problem -- maybe it's not! The crawlspace isn't used for anything other than access to plumbing and some electrical lines that run through it. I laid some plastic sheeting and cardboard on the floor when I had electricians running some lines (just because it was gross in there, and I thought I'd be nice.) I finally pulled the cardboard and plastic out after about 6 months and there was a lot of moisture under the plastic. The cardboard that was touching the ground was nearly decomposed. Should I put some kind of vapor barrier down to keep the moisture out? The crawlspace is under the kitchen and it just doesn't seem very clean to have that lurking down there! The idea of hauling bags of Quickcrete down there doesn't sound like fun, but I'm thinking about it -- would that be crazy?

I have a 2-by-8 cathedral ceiling to a shed roof that I want to insulate as much as possible without dropping the ceiling. I have bought a box of Duro-Vent baffles, which come in 22-by-48 sheets which can be split into 11-by-48s. My rafters are on 16-inch centers. When I staple these to the sheathing, should I butt the baffles end-to-end right against each other or leave a space? I looked at Pro-Vent, which is made of sheet plastic, not foam, and they recommend putting a one-inch space between each piece to allow for moisture release, but the Duro-Vent box has no directions. Also, since a 2-by-8 is really 7-1/2 inches and the baffle takes up an inch, my present intent is to use R-19 fiberglass batts and then one layer of staple-tab Reflectix facing the "warm" side. Although this is far from R-38, do you think the combination will be adequate for a living space? Thank you in advance for your reply.