Yes, a File cope is the same as a new replica.
If the server replica is encrypted with the server ID, you will not be able to use it locally.
If “Enforce A Consistent ACL” is selected in the advanced ACL settings, then you may have difficulty using it locally. If you do a one way server-to-local replication, the access on the local replica may be updated and allow local access.
When you first access the database locally, your notes client will perform a consistency check, which could take a while if the database is large.
You might also want to run ncompact.exe and nupdall.exe on it before trying to open it with your client.