Unfortunately, a debit card won't help your credit rating at all, as debit cards have nothing to do with credit.

Given the state of the economy, banks and the recent introduction of credit legislation (CARD act), it may prove to be pretty difficult to add new credit if your report isn't pretty close to pristine.

Any card will work outside the US. Most charge a fee, Capital one, Schwab and PC Bank Signature don't. If your credit ain't great, the only one you have a shot with is Capital One.

I'd suggest taking your question to Credit Boards. They are the FT of credit, and have all kinds of advice for credit repair.