We support two shopping cart systems -OsCommerce shopping cart and Agora shopping cart.
OsCommerce is a good starter cart package and can be installed on any site that supports PHP. Shopping carts can be complete packages, from putting items into the cart to buying or they can be used as a cart an then integrate with something like PayPal for payment(checkout). This shopping cart includes the secure certificate.
The ability to charge in international currency depends on payment gateway wich you choose.
For more information about Shopping Cart :
http://oscommerce.com/http://agoracart.com/Regards