Help me understand how this works. From what I can tell, I can appear to be any other real Steam account, right? I don't understand why I'd want to appear to be someone like Helk, for example. Wouldn't that be obvious? 

You can always add a new profile (your own chosen name and steam profile) and use that one instead.

Maybe I'm still misunderstanding. Are the profiles limited to existing real Steam accounts for this to work, or can I make up anything I want?

Existing Steam accounts. Just like you can use Garry or Helk's profile. You add a new profile and that's it. The whole purpose of deepcover is not letting the players know that it is you; not letting them know you're an admin. So when you do /deepcover, your name won't appear green (default for admin) anymore.

I understand hiding my admin status. But, I run a relatively quiet server. Showing up as Helk will immediately give it away. Do I just look up people's names/SteamID and create profiles as those? Could I use yours, for example? If someone where to then view players, would it go to your actual profile? 

Merged post

Update: I used my son's Steam name/id and have been masquerading around as him. Everything seems to work well. However, Battlemetrics shows me as being online. I created a profile named Test with a steamid of 1. I showed up as "Test" in-game, but I don't have a way to verify how it looks from someone else's perspective (can they load a profile? Do I show up in "view players"?)