Hi, @Zoemerchandise !
Thanks for your questions. I'll break down my responses in the same format just to make reading this back as easy as possible:
1. There's a couple of reasons this might happen. The first would be that there are multiple shops open using the same email address and credit card and the second would be that the shop has reached it's billing threshold. Typically Shopify will only charge you once a month You receive a bill whenever the total of your transaction fees and other outstanding charges exceeds your account's threshold. Monthly subscription fees are included in your running total, but they are not included in threshold bills. You should be able to determine if both bills are from the same account by clicking Settings > Billing from your Shopify admin and matching up the invoice numbers.
2. We have merchants in more than 150 countries, of which the United States is our largest market. We charge universally in USD so that we are in the local currency of most of our merchants. Further, USD is one of the most frictionless and widely known currencies and making it the most effective way to accept payment at this time. This may be something we revisit or explore down the road though.
All the best!