How do I see what level they are ? Is there a menu I can look in or something...?

Also..

If you get a new merc to follow you are they the same level as you or do they start out at a base low level? I been using boone and I've never even seen him level up but I saw the issues that veronica has. Apparently she doesn't seem to level with the player or something, some kind of script issue.

So that got me thinking if that happened to boone because like I said, I've never received a msg telling me that he has leveled.

Assuming you mean followers and not Freeside mercs..

They don't say that they leveled up.. Ever. They just do. There isn't a message. For Boone or anyone, but you..