About the issue of how to tell whether a book is PDF on the new site, I found these two versions of a book on the US site and checked the ISBNs on the old site, so I know the first one is Adobe DRM EPUB and the second is Adobe DRM PDF:
(EPUB) ISBN: 9781616961190, Read this on: Desktop, eReaders, Android, Tablets, IOS, Blackberry.
(PDF) ISBN: 9781616961183, Read this on: (no devices listed)
So it seems possible to tell PDF from the devices listed. This is just one example though, I don't know if it is consistent for all PDFs.