One thing I found with shipping internationally is that some buyers might want you to declare a lower value on an item in order to lessen a customs charge. Problem with that is that you won't be able to insure past the declared value, and if the item is lost or damaged, you will be out the difference. I don't like to do that, but if the buyer insists I have required him to agree to accept the risk of loss after I ship, which of course goes against your desire to keep the risk of loss. For that reason I have started limiting my sales to domestic buyers only.
For the weight you're talking about, I think you might not be able to use UPS. There are some international freight companies, hopefully other members will chime in.