... And did read that you said to put the vapor barrier up first, then put up the insulation on the bottom of the joists. So, that's clear now.
And to agree w/you, how one goes about deciding what to do when it comes to insulating and closing the vents, it depends on where one lives. In SE PA, for example, which is where I live, the bottoms of the joists are insluated (and/or vapor-barriered.) Not even as a retro fit. The vents are not closed off either. What 'we usually do is insluate the floor between the joists with R-30 (or better), along with insulating the pipes, et. al.. Even the walls aren't insulated. The crawl is essentially treated as being outdoors.
Down the NJ shore, I see this methodology being used on new construction. Granted, it's about 5-10 degrees warmer there in Winter than it is where I live, and these locations are only 60 miles away. Again, I'm agreeing - If 'you' are getting conflicting information, it's certainly best to find out what's done in your particular area under the SAME conditions/circumstances.