I don’t think I could recommend handing out a corporate ID to ex-staff.
On a fresh installation of Notes, you will be asked, if you want to connect to a Domino server. In corporate environments, you usually say “yes”. However, if you choose “no”, Notes will create a “generic” id for you, that is not derived from any corporate certifier id. This is all you need for POP and SMTP.
I don’t remember, if you have the same choice through the reconfiguration wizard, or if you clean the notes.ini (except for the first 4 or what lines). But given, that there are other dependencies with the fully hierarchical name the user has now (like location documents, to name only one), I would definitely recommend to delete the current id form that machine and do a fresh, stand-alone installation.
I don’t remember for sure, for how long this generic id is valid, but it’s probably for something like 100 years.
That should work. Normally, you have manager access to local databases anyway (unless they have been created as replicas from server based databases).
But I think I would rather make a copy of the existing local address book using a different file name and then just copy over the required contacts and groups. If you use the old address book directly, it will still contain the old location, connection and certificate documents, which may lead to unexpected and undesired results.
What about all the stuff stored in bookmark.nsf and and desktop6.ndk? I would be a bit concerned about things like old server names in the File → Database → Open dialog (which I was never able to track down completely). That’s why I put more emphasis on the new install option.