Curious on how when a player hovers on another plays torso, it would say their username?
I would take a look at Billboard GUIs. Billboard GUIs are prefect for what you want to do because they are not only relative to the players position (and camera position) around the object it is placed inside, but you can also set an Adornee
of the Billboard GUI. Setting the Adornee to a specific player will make the Billboard GUI display only for the Adornee. For example: If the Adornee is set to my username MezornoIV, the GUI is only visible to me, and invisible to other players in the session (which will help you out immensely).
If this answer is unclear in any way, I'm more than happy to explain it to you.