1. As per his logic, you have not complied with the terms of the agreement for sale for which the agreement stands cancelled. Based on this ground, he may sell his property,
2. He can do that if the said agreement with tyou stands cancelled for non fulfillment of its terms,
3. File the specific performance case against him with an application restraining him to sell the property before the suit is disposed of,
4.It was valid till you violated the agreed terms of payment,
5.File specific performance case against him,
6. This application will be of no use. They can not refuse to register a deed unless directed by the Court,
7. Yes, file the specific performance suit and also for the restrain order as advised above and in my earlier post.