Each individual person has a mail file on the server. The file name and path are stored in the Domino directory (names.nsf) on the server. At the very least the mail file will contain the person’s mail and calendar information, but may also contain their contacts depending on how mail/contacts are set up. (Other terms come in here like iNotes/POP/IMAP/Synchronize Contacts which would all mean that contacts could be stored in the person’s mail file.) All of a person’s messages reside in one NSF file by default. Through the use of Archiving and/or Domino Attachment Object Store (DAOS) that can be modified somewhat.
One client twist is that a person’s contacts can be stored locally on the Notes client in their own Personal Address Book (names.nsf) and kept only in that local database. Most other non-configuration information is kept on the server.
You have touched on a major source of confusion in Notes/Domino that goes way back. There is a namse.nsf on the server that is the public address book, and each client has a personal address book that also has the filename names.nsf, but functions very differently. A client may have a local replica of the public address book, and must change its filename in his local directory (we use names0.nsf for the local PAB replica).
A Role is part of the ACL to a database.
This is a design element that is added by the developers as an extra restriction to the database itself. The names.nsf (on the server) has many like USER CREATOR / GROUP CREATOR and more… (PUBNAMES.ntf)
The personal Address book Names.nsf (Pernames.ntf) as has simular roles.
Roles in the ACL in the admin help for more information