Found my answers.  SRM user is whomever the service is set to run as on the SRM server.  By default this is "service."  This user will need the "StorageAdmin" role.  VSI user is the userid of the person running the GUI.  Their userid gets passed along.  The user authentication role can be "Monitor."  For host ACLs, the permission needs to at least be "Base" to allow discovery.
Currently we are in the process of setting up security on our V-Max arrays, both host ACLs and user authentication.  This means that access to the arrays will be locked down to specific hosts and specific users from those hosts.  That said, I am having a real problem finding out how to setup VMware  SRM and EMC VSI Viewer in a "secure" environment.    In the SRM documentation provided by EMC, there are references to the required host ACL setup for Symmetrix.  However, there are no comments about the user authentication setup.  For example, what user does SRM  run as?  Also, what role does that user require in the user authentication schema.  In the EMC VSI Viewer documentation provided by EMC, there is absolutely  no comment about security for the Symmetrix.  So, what user does VSI Viewer run as, what user authentication role does it need, and what  host ACL permissions does it need?  Any help you can give here would be appreciated.  Thanks,  Will
Symmetrix Security with EMC VSI Viewer and VMware SRM