Sir,
Answers for your qurries are as follows:-
Query1: Yes it is composit supply since it involves export of goods and service since as per Section 2 (30) of CGST Act, 2017 " “composite supply” means a supply made by a taxable person to a recipient consisting of two or more taxable supplies of goods or services or both, or any combination thereof, which are naturally bundled and supplied in conjunction with each other in the ordinary course of business, one of which is a principal supply."
Query :2 Shipping charges are subject to IGST since the export of goods are on CIF basis the exporter has to bear the freight charges. Since the exporter is located in taxable territory (India) and he is bearing the freight charges, the exporter is liable to pay IGST.
Query:3 Yes.
Query:4 Yes.
Query:5 Yes, IGST paid on shipping freight is refundable since the service is an input service for export of goods.
Query: 6 Yes. As per Sl. No.19B of Notification No.12/2017 dated 28.6.2017 as amended by Notification No. 2/2018- Central Tax (Rate) dated 25.1.2018 CGST chargeable on service by way of transportation of goods by a vessel from Customs Station of clearance in India to a place outside India is Nil. Bit this exemption is available till 30.9.2018 only.