Can traders get the credit of IGST paid at the time of imports for discharging their domestic liabilities under GST? If yes, how?

Yes. Under GST, traders will be on par with manufacturers. IGST paid at the time of import will be available as credit which can be used for payment of taxes on further supplies. GSTIN would be used for the purpose of credit flow of IGST on import of goods and refund of IGST paid in case of export.