Whether Input Tax credit can be availed on advances made to supplier or service provider?

Answer 1

No, If advance payment was made before receipt of goods and services, input tax credit cannot be taken as goods and services are not received.
At the time of payment of GST on advance, the supplier of goods and services cannot issue tax invoice. He will only 'receipt voucher’ and Receipt Voucher is not a valid document to avail Input Tax credit.