Yes, PAN is a mandatory requirement without which the return cannot be filed. The responsibility to procure PAN from seller has been vested with the buyer.
The buyer would have to file two Form 26QB for each of them in their respective share and will collect the details of both accordingly.
No, only if the cost of transaction exceeds Rs. 50 lakhs.
No, only PAN of both seller and buyer is sufficient.
The buyer will deduct TDS from the payment he's suppose to make.