The foreign credit card thing is probably a security issue. It could also be a pin & chip issue, as most European banks are now using this technology (at least in the UK) whereas this is not in sight for the US credit cards.

I would pick the tickets up in person. Like another poster said, passport control and customs are usually a breeze, as is security (compared to airports at least) so get there an hour and half early and you should not have any problems.

I would do this rather than mail the tickets to the US.