@barry_van_dijk ,
Replace Process Level Token - is an equivalent of setuid on UNIX. This right is required in order to start a process under a different user account such as with the CreateProcessAsUser() Win32 API.
What does the privilege do in relation to the SAS Viya software?
Starts the CAS processes on behalf of other users, if necessary.
Is this privilege necessary during installation only or also while using the environment?
That is required while using the environment.
Does the account need to remain enabled after installation, or can it be disabled afterwards?
Yes, the CAS account should be enabled at all times.
Can the account's permissions be limited by the option 'Deny log on locally'?
No.