You'll need some sort of account# with USPS/UPS/DHL. Depending on commerce platform you should be able to just import an CSV with rates.Barring that, I need to actually know what to plug into the commerce platform so they can calculate shipping.
As for overseas sales, they should be able to be sent as regular letter (how heavy are the coins?) instead of being sent as a parcel, which ups the price dramatically. Tracking adds to the cost of course. But as a scandi I usually take the risk of no tracking instead of having to spend $40 to get something sent here.