A. Directory

Before Experts, Managers and Entry Points can be used in Instant Queue Manager, they need to be registered with the Queue Manager.  After having created the userids in Sametime/Lotus Notes Address Book.
Experts are the people that will respond to the visitors' questions and comments.  They usually will not have the ability to create and modify queues. 
Managers are the supervisors and staff responsible for overseeing the queue.  They also have limited ability to modify queues, usually limited to adding/removing experts and enabling/disabling experts.  Managers are also able to review statistical reports and monitor the queues. 
Entry Points aren't people at all.  They are the queues themselves.  They usually are userids that closely resemble the name of the queue itself, though there is no requirement for that to be the case.  These userids allow the queue to connect to Sametime and interact with the experts and visitors from a central position in the conversation.  It is this userid that will display in the Sametime Contact list as the queue.