Overscanning includes the frame edge by definition. If there’s gate weave, you can increase the amount of overscan a bit (in the scanstation this means you output a slightly larger file with a bit less crop) to ensure the frame edge doesn’t go outside the bounds of the file edge. But it’s rare that this is needed, except with elements that have been duplicated optically from old or damaged films.
We always approach scanning from an archival perspective, so we treat new and old film in basically the same way. One can easily duplicate the softening that happens in optical duplication, digitally, if that’s the intended look. Thus, the film should always be captured in such a way that the result is as close to the image on the film as possible. One way of looking at it, that I find helpful, is to think of scanning the film, not the picture. Our job is to digitally reproduce the film as closely as we can, not so much the picture the film contains. Color/grain management/noise reduction, all that stuff that used to be part of the telecine chain should be completely decoupled from scanning, because all of it can be done as needed in post now.