Cheque bounce

If he had given the cheques for repayment of the advance amount then it becomes legally liable debt. Hence, the cheque bounce case is very much maintainable.

Certainaly yes, you have proof of transaction and you have the instruments, if he fails to pay just file caomplaint under 138 NIA along with recovery suit for recovery of amount

The notarised agreement to sell is a valid document to enforce it against the drawer of dishonoured cheques and complaint u/s 138 of NI Act is maintainable.

From the facts stated by you, it is presumed that possession of the property was not handed over.

If the possession of immovable property is not handed over under an agreement to sell, the question of registration  does not arise. In any case in an offence relating to a bouncing of a cheque , the ingredients of section 138 are to be fulfilled.

If those ingredients are satisfied, the non registration of the agreement to sell will not be of any hindrance to the filing of a complaint under S.138 after due fulfilment of the provisions of the NI Act.

Possession of a property is handed over (generally) at the time of execution of title documents and not (normally never) with "agreement to sell"

Yes, you can initiate steps as provided under Section 138 of the NI Act.

Agree with the views of Dr. J.C Vashista. However in cases where agreement for development/construction is entered into, possession is handed over which requires registration. That may not be the case here as it looks like an agreement to sell simpliciter S.138 is maintainable.