I'm doing a Mastes Degree in Library and Information Science at the Cologne Technical University (Fachhochschule Koeln). I'm writing a thesis about non-commercial publication models of scholastic writings. Your distinction between pre- and postprint and the definition of eprints as all of them is clear. However, I think that they also differ from each other not only because one is refereed and the others are not( yet), but because the preprints could never be accepted by the referees and therefore be "notprints". What I find very important and even more essential is your distinction between RES and PRES, but I think that there is some inconsistancy in saying that preprints are not publications and try then to apply peer review (something typical for publication) to them. In my opinion it would be better to make no distinction in scholastic writings. Preprints and postprints should be put together without thinking of peer reviews. They could be distinguished at the research output through ranking, depending of whether the autor is member of a University, or the eventual publication. Peer reviews should then be used in other contexts, like a publication platform at a University server.
Thank you and Regards Maurizio Grilli