Inquiry regarding customs clearance and VAT for trade involving non-payment (payment in kind)

We intend to transfer (export) equipment installed overseas to Korea or a third country, and we plan to proceed with this as "trade with non-payment of funds." Since there is outstanding debt between the overseas shipper and the domestic shipper, we are selling the equipment assets to the domestic shipper as payment in kind to settle the uncollected funds; therefore, no actual cash movement will occur. I would like to inquire about the following: i) Is a sales contract required to be submitted to local customs during export clearance? ii) Are there any restrictions on the Invoice Value in the case of trade with non-payment? iii) If proceeding via trade with non-payment is not possible, will VAT be incurred locally during a standard export? iv) If VAT is incurred, what is the percentage? v) If customs duties and VAT were paid when the product was originally imported from Korea to the overseas location, can we be exempt from paying VAT or receive a subsequent tax refund upon re-export? vi) If we do not receive the proceeds from the equipment sale after the export license has been issued, will any post-clearance issues arise locally regarding the issuance of the export license?