Do I need to pay IGST for Export even if my turnover is less than 40 Lakh ?

Yes, its mandatory.                                           

Ok, this means -

If I am only selling tangible products as a trader within India (no export business) and because my turnover in the past year was more than 40 Lakh but for the current year turnover is less then 40 Lakh then I don't need to add GST in the selling price invoice (even after having a GSTIN) ? correct my understanding if I am wrong

If I am selling (exporting) tangible products as a trader outside India and because for IEC it is mandatory to get GSTIN so I hold GSTIN now even if my export turnover is less than 40 Lakhs still I have to add GST in the export selling price (if not using LUT) and then I can claim based on shipping bill ? correct my understanding if I am wrong

I know that can be refunded but here my question is that why should I add the GST in export selling price (if not using LUT) at the first place if my turnover is less than 40 Lakh (as a trader for tangible products) ?