As an ATC I think that the POB is a crazy question. The fire brigade are going to keep going until they are assured there is no one left, it will make little difference if they know how many were there in the first place. I can understand that if say an A380 landed with an emergency that was only carrying 15 crew (eg), then the local emergency services will benefit from that info and not send the entire county to the airport should the need arise, but surely the handling agent is capable of providing POB quite quickly?
As for fuel remaining, I think there are three main reasons to this. How long can you fly for, are you landing overweight, and how much flammable material will the fire brigade have to deal with if the landing doesn't go to plan? I'd ask exactly what is required rather than "how much fuel do you have remaining" to satisfy whichever agency needs to know.