2. There is a watch that is referred to as the 1921 because it was first introduced that year, but this watch is not related to the 222 or Overseas.
3. Only the later versions of the OS allow for interchangeable metal bracelets, rubber and leather straps. Previous VC "Sport" watches come with metal bracelets only.
4. None of the watches from you web link have transparent case backs that allow you to see the movement. Also, the OS collection does not have a watch with a transparent case back. As Celter mentioned, if the watch you are looking at has an exhibition back, then I highly doubt it is an Overseas.