Just a note; You don't "click" anything. Mouse over as in your reticle (crosshair) meeting with an actor, that is in. But otherwise, we do not have typical mouse overing (except in Menu's).
So you are saying everytime I mouse over/aim at a target their name plate is going to appear?
Edit: Sorry that wa a bit blunt. Basically I am confused a how I interact with other players and NPCs when not in combat. Can I select other players in some way so I can easily whispher, invite, ignore them? Or how do you see this working?