Ah good morning Flower!
If I have a dire emergency then being able to talk to my favourite approach controller will not help me, though if I am going to hit the ground I will let the area controller know where to send the ambulance.
What sort of emergency did you have in mind? If I can't make an airfield with the required facilities then apart from setting the emergency services on their way there is little you can do for me.
If however the emergency is less dire you can help me with vectors, let-downs, landing priority etc. In which case I will be wanting to divert to your nice big airport.
Pilot controlled lighting is a facility for turning the runway lighting on by keying your transmit button in a set sequence and is quite common at unmanned fields in the US.
Mike