Excellent post and excellent questions.
In short, the answer to all three questions is a decided YES!
As to where to get your hands on some, I have vintage Guerlain Vetiver EDC and EDT, vintage Santos de Cartier, and vintage L'Occitane Vetyer on my decants list which will be back up sometime in mid May.
Stayed tuned over the next month or two when I will be completing comparative reviews of all three fragrances and the differences between their vintage and new renditions.
[red]P.S. I will also try to procure some vintage Caron Third Man and undertake a comparative review of the changes between it and the current version. From my scent memory from way back in the eighties, the difference is huge.[/red]