The default currency in Cydia currently is US dollar. Is there any way of changing this, or at least bundle multiple payments together, as the AppStore does?

I end up paying 1.88£ for a $0.99 app, as it slaps 1.25£ onto each payment in a foreign currency. For more expensive apps, MyWi, this doesn't matter so much, but all those smaller cheap tweaks/apps double in price.

Don't know.

But world is using the buck as it's default currency, they in process of crashing it and replacing it, but for now it's buck. Where I'm at you could open up a USD bank account, they give you a visa bank card. Very convenient, as you can receive money to it without any fees. Since you'd be needing that in the future, why not open up one.