Hm, if you're using the Cart Discount method, then those discounts would apply to any/all shipping, regardless of destination, so with that approach there's no way to also have Int'l shipments always be the same, undiscounted flat rate regardless of order amount. If that's fine and you just want Int'l orders to have a $12 max. basis but using the same discounts, we can explain how to set that up.
Otherwise, we can help explain some other approach. You may find it helpful to know the basic formula we follow when calculating shipping charges for each order:
(rate X (total product wt. + container wt.)) + (container cost) + (handling cost)
Note that you can "game" the formula by applying non-literal figures for various settings, so the formula adds up the way you want. For simplicity, I've left out the matter of ordered Quantity, which of course affects the total product weight and could multiply certain container weights according to what Packing Capacity you configure for each product.