I think the problem is solved, and would like to conclude the post (as long as nothing else goes wrong).
I forgot that this was a Dell, so I realized I could call customer support, last computer was a home-built. They checked everything that was already done before, even reflashed the drive, finally concluding that the Vista installation was corrupt (the drivers should have been there, but were not).
Since this was a fresh install (by me), it wasn't a problem to redo it. But I did re-reflash the DVD drive to RPC1 (provided by MCSE, check box) before reinstalling Vista.
This time Vista did not complain about missing drivers (yeah!), and the DVD drive, for now, seems to be region free.
That is, I put in a region 2 disc, and neither DVDShrink nor VLC Media player complained. The same thing for a region 1 disc, then repeated the process with Windows Media Player.
You can see in the device manager, that there are now driver dates (that looks a little better), and also the Region Code tab is missing (strange).
WMP choked on both the region 1 and region 2 discs.
So, my suggestion in conclusion, for someone who wants to follow my path is 1) be careful, and 2) it may be necessary to reload Vista after flashing the drive (this could have been my goof, too, because following advice on how to 'slim down' Vista, I deleted the C:\Windows\system32\DriverStore\File Repository directory. Was worth 1.2 GB!)
And of course, if I have more problems, I will come crying back to here...
Thanks you all!