1. The Society Bye-Laws states that NOC is not required for Sale of Flat. However said Society NOC shall be required by Buyer party for any Bank Loan formalities.

2. It is mandatory for the Society to keep a photocopy of the members Sale Agreement, on its records, for all futuristic references and to maintain its records & registers, without which membership transfers is not possible. There is no legal risk in giving photocopy of Sale Agreement, to Society and neither it can be misused in anyway, since nowadays all property transactions are compulsorily computerized and needs to be registered in presence of Seller & Buyer parties.

Yes, but the society must have the copy of your sale deed. Initially at the time of formation the society every one's sale deed is kept with them.

1) society can seek copy of sale  agreement from legal heirs to furnish NOC for transfer of flat 

Yes, the society needs a copy of sale agreement to give NOC. and charge transfer charges based on amount of sale.

For NOC the society for it's record may ask for copy of sale agreement and deed.

 If the rules mandate that copy has to be given then it has to be complied.

No, only legal heir certificate if society wants to confirm legal heirs of owner.

Yes society can ask for a copy of sale agreement for issuing NOC for transfer of flat. 

Society need a copy of sale agreement to issue NOC.

No there is no such mandatory provision. They may inspect the agreement. 

This is a matter of bylaw of the association.

If the bylaws makes it mandatory then they may have to comply with the formalities.