This is the visual section so I hope talking about the HUD is okay here. It is visual after all. :P

Right now I have the player see other player's names when they have them centered on their cross hair. The way they see it is through a text object on the HUD just below the center of the screen. In that case I like it, but I'm not sure I would like to show interaction that way. I think it would feel like overused space and not very creative. Does anyone have any ideas of how I can show the player that they can interact with something? I was thinking something like BF3 or BF4 where when you walk up to something text will appear in 3D space to show you something, or a simple glowing outline. Any other ideas would be nice to consider.

You could change the crosshair image; perhaps a reaching hand, a set of cogs, or something else, according with your particular game. You could even have different crosshair images for different interactions: a half-open door for doors, cogs for machinery, speech-bubbles for communication with NPCs, and so on.