Reverse charge

Dear Sir,


Please guide us in case of following 


1.  One of my client which is in Delhi,  getting the commission from out of India in foreign currency.


a.   In this case have he deposit the IGST under reverse charge or not ? 

b.  If deposit the GST under RCM then can he claim the refund against the same ? 


2.  If we purchase the material from unregistered dealer & on the same, we have to pay the GST under reverse charge. My question is that where & how it will be declare I.e. in GSTR-1 or GSTR-2


Please guide us in case of above on priority.


Thanks & Regards 


Pradeep Kapoor