Regarding Sale Consideration Amount ?

I am planning to buy a plot of land. The plot belongs to person 'A' as is reflected in the revenue records. Person 'A' has authorized person 'B' as his attorney (registered general power of attorney) for selling the land. I have the following doubts: 1. Is it valid if I purchase the plot from person 'B' after he/she gets registered power of attorney from person 'A'. Should I go ahead or not ? 2. Person 'B' will be signing the sale deed document during registry in sub-registrar office. Who will receive the consideration amount - Person 'A' or 'B' since person 'A' is the real owner. If I pay consideration amount to person 'B', then person 'A' can later on ask me to pay the amount? 3. Normally, in the POA it is mentioned that person 'B' will execute sale deed in sub registrar office. Does 'executing sale deed' also means that person 'B' will also receive consideration money? Or it is to be mentioned separately in the POA that person 'B' will receive the consideration money? Please clarify and explain. Thanks