Please check out the shared groups feature – it lets you define groups of users and have those users automatically shown on people’'s rosters.
On the state description – I’‘m not quite sure what you’‘re talking about. Do you mean their resource or their presence status message? Whether either is shown is up to the client you’'re using.
The presence service has a mode where user subscriptions aren’'t required – have you tried that out? It will let you get presence for anyone in the server when operating in that mode.