Power of attorney - query

My Wife stays in Kolkata, but I stay in Mumbai. I own a property in Kolkata.I now want to sell it and intend to Grant a Power of Attorney for carrying out the sale as i do not stay in Kolkata. I have five questions -

1) Would we need a Special POA in this case or a General POA would do ?

2) Would the POA need to be Registered and with whom ?

3) What would be the likely Charges for Registering such a POA ? (Stamp Duty need to be paid ?)

4) Would the POA need to be Registered in a MumbaiCourt (Registrar) or in a Kolkata Court (Registrar)?

5) Finally, what would be the correct process of Registering the POA ?

Thanks in Advance to All.

Ashish Masand.