Pre-sale Pro version questions

We would like to use this in tandem with WooCommerce Subscriptions but need to know if this is possible:

– Prices are set the same for USA and Canada but users are charged in their home currency (effectively making the subscription slightly higher in the US)
– Existing customers should be “grandfathered” in and continue to pay in the currency they are currently charged in (CAD – shop default)
– This would need to be the way the pricing works each month when it is renewed.