I\’m not sure if I\’m late with this answer but hopefully it might be of atleast some help to someone.

So, basically, when you are getting into a Dropshipping business with a Chinese supplier & selling the products in USA, this does NOT come under the definition of Indian GST law.

GST would be applicable ONLY when the goods/services are originating in India or entering India & then being shipped again.

In this scenario, nothing of this sort is happening in India. However, the payments you receive would definitely be liable to Income Tax, as per your income slab.

Now coming down to your specific questions:

1. Company registration (Pvt Ltd/LLP) is NOT mandatory for this. You can go ahead & carry out operations as a Proprietorship firm or a Partnership firm as well. It depends solely on your choice with respect to the features & liabilities of each type of company/firm registration.

2. Like stated above, GSTIN is NOT mandatory for the type of business you have mentioned. It would have been mandatory had you wanted to do an ecommerce business in India. In that scenario, ecommerce being interstate business transactions by it\’s nature, GST would be mandatory irrespective of the turnover.

3. Paypal would deduct it\’s standard fees from you & add an 18% GST on this. If you have a GST number, you can submit that to Paypal & claim input for this GST paid to paypal. Without GST registration, you cannot claim this as input. So, basically, No difference with or without GST except input claim.

I hope I was able to make things atleast a bit clearer for folks confused with this aspect of dropshipping. Even though I have tried to explain everything to the best of my knowledge, I strongly suggest that you should discuss your business/dropshipping basics & my above points with your CA or accountant for clarification.

Please do note, most of our experienced Indian CAs & Accountants are not very much familiar with ECommerce businesses & not at all familiar with dropshipping concepts. So explain in as simple terms as you can so they can guide you properly.

https://community.shopify.com/c/Accounting-Taxes/GST-for-dropshipping-store-in-India/m-p/775815#M3967

Thanks a lot Abhishek. You were of great help. You have answered things which none of the people I consulted know about. 
 I have already registered as Proprietorship and has taken my GSTIN number. I still have one query for you. 
Now, as per your advice I need not declare my monthly GSTIN returns, all I need to do is file my income tax once, in the month of March-April.
Am I correct?
Also I just wanted to know if you are CA person? Also the source of the information you have provided me, Just for my reference and to help the CA guys (whom I have already consulted), to mention such a clause exist in the dropshipping business.
Once again Thanks Abhishek.