Underconstruction flat purchase in Pune

Hi Sir/Madam, I have purchased an under construction flat in Pune. The posession of the flat will be next year. The total saleble area of the flat is 1032 sq ft and the carpet are is around 780 sq ft. I am going to do the registration in next few days. I have following queries; 1. Builder is saying that he will mention only the carpet area and the property value in the agreement. Builtup/Saleable area will not be included in the agreement. Please suggest if it is ok to have only the carpet area mentioned in the Agreement. 2. Builder is asking for the cheque for Stamp duty and registration fees should be in the name of their lawyer. Is it ok? Also, Can I hire my lawyer for stamp duty and registration as there is an aditional demand of 10000 rs towards the lawyer fees. 3. Service tax (3.50%) and VAT (1%) payment is also asked by the Builder, Do I need to make this payment during the agreement or later during flat possesion? 4. Also, How much is the stampduty and registration charges in Pune. Thanks and Regards, Deepak Sharma