Need process document on import purchase orders with customs duty and other tax's involved.

Hi experts, we are implementing Oracle for one of the client and their requirement is as below.

"System should support a robust imported purchase facility including LC, custom clearance status, foreign currency rates freezing by date or based on date of shipment, etc"

We are handling VAT and other local tax's but we are new to Import PO's where customs duty is involved, I got some information from one of my friend that process will be create PO with currency as USD and later create BOE in INR, validate and pay the BOE Invoice and apply this BOE in Receipts localized screen for the Receipt against PO created earlier. I am not sure if its correct or any other process is involved. Please help me with screenshots on the process cycle. LC means I believe its Letter of Credit, is there any option