Unless you purchase and download a file from Qobuz, adding it to the library just keeps a record about the album, and how to get it from Qobuz in Roon’s database. If Qobuz removes the album, they will be inaccessible.
DSD files woulkd be added the same way as any other ones, just put them in Roon’s watched folder.
You need to open up a file manager window to the internal drive of the N1 and then copy from the PC to the N1. See the SMB step, don’t use the drag and drop method…