INBOUND TOUR OPERATOR

Please advise

We offer inbound tour operation services to overseas client comming to India.

Client are unregistered.
Address of clients are overseas.
Arrival of embarkation of client are mostly Delhi.

Now: 
1.what % of IGST we have to charge 5% or 18%
2. What shall be place of service? 
3. As we receive payment in convertible foreign exchange, do we have to put it in export of services? 
(6A EXWP) or shall we put it in B2C(L) or B2C(S) in GSTR-1