A#1:
National Finance Commission (NFC) award, is a sort of formula of distributing provinces income by Federal Govt:.

A#2:
Yes it benificial to some provinces in my point of view, as If I take example of Custom Duty (as an Income).
Most of the Custom Duty is colected in Karachi, now with this NFC Sindh has to share this with Federal Govt: so he might lose some money here from Custom Department, in the mean while Sindh might be getting his share from Tax Generated by Punjab.

(@Members: Correct me if I am wrong)