Google Checkout Expert/ Developer

Google Checkout: We have google checkout currently set up on our site. However, we need some added features. We want to add the ability for people to buy from around the world, so if people are shopping from a country other than the USA, they should be able to select their country, and the price should be converted to their currency. The shipping cost for the international location should also come up automatically. We also want to provide certain discounts. Please don't bid unless you are confident about doing this project. We will check references.