Regarding CT-2

Dear C-2 for is no more applicable in GST Regime.

Yes for Merchant Export in term of Notification 40/2017 CT (R)
merchant exporter can pay a nominal GST of 0.1 percent for procuring goods from a domestic supplier for export.

& it's mandatory for Merchant Exporter to Export procure goods with LUT & in term of circular 94/13/2019 GST , the Refund can be claimed by Merchant Exporter for Unutilized ITC

But for procurement of central excise commodities, i think it is mandatory.