The foreign debt is in Euros.
Yes, yes it is. And that's why Greece is f*'d. Entering into a currency union with a bunch of other nations that have very different economies and politics was a really stupid idea.
Also, government bonds are usually denominated in the country's currency. That means you can always run the printing presses to pay off your foreign debt (something people often forget when discussing US government debt).
That doesn't really help. If they print more than they produce, the currency will drop in value.
That's the whole point. Devaluing the currency means everyone in the country takes a pay cut, at least with respect to imports. but internal prices don't change (at least not immediately). This has the effect of discouraging imports and encouraging exports. Taken to extremes it will mean hyperinflation and financial collapse but used judiciously it's a good economic tool.