If you have a code you can apply it at checkout. Discounts won't show until you reach the checkout stage (one step after your cart).
You cannot use your discount code with any other offers or promotions that use discount codes themselves. This includes bundles.
Prices should automatically display your local currency. If we're having trouble identifying your location, the prices will revert to USD as this is most widely used currency.
Providing we can identify your location, you'll check out in your local currency.