Time to get Amazon JP prime....no account linking correct?
no, Prime doesn't link up and i don't believe they'll allow it for overseas anyways.
Yes, you'll need a credit card. Best bet is VIsa or Mastercard. Never been able to get my DIscover to work.
Older DS games are gonna be hit-or-miss on availability. As they are likely to be sold by third party retailers who will NOT ship internationally, you would need a proxy. If anything, Amazon will have a new copy that is way overpriced.
AMEX works as well