I knew this would come up eventually. USPS uses a non-standard country code for the United Kingdom: UK instead of GB or vice versa, I forget which. If you're not sending country information to anyone else (like UPS, PayPal, etc.) you can go ahead and change it directly in the uc_countries table. It's not the best solution, but it's a quick fix. I'll see if I can find the other changed countries and hack in a real solution.

I'm afraid I don't know what the deal is with the shipping weight problem. Maybe the international quote method wasn't updated along with the domestic one, so I'll review it again.