I have confabulated :) with Henry and I, too, have a poured crawl space.
I happen to get a little water during heavy rains due to the grading/slope on one side of the crawlspace. Unfortunately for me, the grading there slopes TOWARDS the house over a distance of about 6". This is enough to allow water to run down the outside wall and make its way into the crawl space. My space is 30' x 15' x 3'. I has 2 cement block sized vents. The 'ceiling' of the crawl space is insulated with R-30 fibreglass insulation. There are right ways and wrong ways to do this job so I'd do some reading first. Also, I live in SE PA and i insulated my heating ducts and water lines before I insulated. It's the only way to do it. I may even need to add another vent because I think the existing 2 vents are inadequate. (I'll look into the forumla before I start busting-out a block ...) As Henry says, and particularly in my case, I leave my space vented all year 'round. Since I do get a little water, I HAVE to keep it vented so that when it evaporates, it has a place to go.
Everything else he discussed sits well with me. My best to ya and hope this helps.