Upgrading rooms nets harder incidents, not more or expanded ones. So in theory more babies and people =/= scaling events. But I may be wrong.
The radio station doesn't train anyone inside of it.
It uses power to do what making babies already does. (bringing in new dwellers and raising happiness)
The radio station is the last thing anyone should be fully staffing, it pulls people away from making resources or scavenging the wastes. For only a *chance* at getting a new level one character about every 2- 3 hours. Whereas I can make N number of new dwellers through babies every 6 hours. IF it pulled in people with better stats or levels it would make a lot of sense.
The happiness bonus out of it only really helps when things are going fine, if you have radiation or food problems then it doesn't help. It is really the last thing to be staffed, only when everything else is peachy. The only big use I see in it is bringing in new blood that can be used to make babies with as the family trees start to get f'd up.