100% wrong. Greece's interest rates would be the same or higher if they controlled their own currency. Assuming they allowed the market to set long term rates, the rates would include expected inflation from printing to pay off the debt. If they did what the US is doing and had the central bank buy most of their long term debt, then interest rates could be low but the exchange rate would reflect the monetization of debt.
100% wrong. This current crisis has shown that conclusively; every last country that controls its own currency has significantly lower interest rates relative to their debt to GDP ratio than do countries in the Eurozone that do not.
What's funny is that people have been predicting exactly what you describe for years now, and they have been wrong over and over and over again across numerous countries, in both the actual interest rate and the relative exchange rate. The ECB is prohibited from monetizing debt, and even if there are workarounds they have not done so at the rate the US has... yet the dollar is flat vs. the Euro since the crisis began and the GBP has gained despite them monetizing their debt (and having low interest rates).
What you're saying is just not supported by reality, nor has it been for quite some time.