In reference to your query please note:
1. GST in your case would be payable on the value charged by the promoter from 1st independent sale, and in case the area of flat is less than 60 sqm and 45 lakhs gross value would be 1%, otherwise 5% if either condition is not satisfied.
2. The taxable value of consideration in the hands of the landowner would be the fair market value of the project including land on the date of execution of the JDA. Further as per Section 45(5A), such tax would be payable in the year when the transfer takes place.
3. Yes the benefit of 54F would be available to you subject to the conditions laid down therein.
4. Yes as a landowner you can very well sell your share of flats, however conveyance in this case is not required. You can sell during construction phase itself and you have to charge GST from the final buyer, and you would be eligible to claim ITC of GST charged by the developer to you, provided the rate you charge from the final buyer is higher than the rate charged to you by the builder.
Please connect in case of any further clarifications.
Thanks & Regards,
CA Aditya Dhanuka.