Not sure about that. I think debtors have more power than creditors. After you have a client refuse to pay you, you start to see creditor/debtor power balance in a different light.
Not sure about that either. I am not sure what I need to google to find this, but I seem to recall reading about countries that devalued their currency, but still were able to get financing. It doesn't necessarily need to be a refusal to pay per say. China asserts that it is their right to keep their currency artificially pegged to the dollar. On the same token, we can devalue our own.