I have played a firefighter these last few days and found a few things that were bugging me about that profession.
First off, I had my sim move into a house that had been struck by a meteor. A fireman stopped by to help (they always do with that scenario), but he is not listed as a co-worker even though when asked he answers that firefighter is his job. I found it pretty disappointing that npc firemen do not count as co-workers.
The second problem was one I created myself: I put down two firestations, a copy of the ea station that automatically is in the bin, and another one that is a copy of the station in the new town (I played my firefighter in Sunset Valley). Only the firestation where i applied for the job is shown as my workplace, but the building is empty 24/7, there is not a single firefighter in there (except for my own sim of course). There are three people at the other firestation who count as co-workers, and I can maintain and upgrade alarms and fire engines at both stations (results seem to be kept separately for both lots, too). The most annoying is that every time I have responded to an emergency the automatic return action brings my sim driving to the wrong station. The game does count her as being at work even if she is at the other station, but the fire engine and fire alarm at her real workplace fall into disrepair quickly and i have gotten several warnings because i forgot to go back to the other place to maintain the engine and alarm there.