Yeah, for some reason the Japanese eShop accepts foreign credit cards but the North American one doesn't.
You can use Visa or Mastercard. I've heard of people using debit, but I don't like using debit for stuff because of fees (like, you know, eff CIBC and all that).
I like to opt for getting eShop cards for Play-Asia sometimes, though.
Gyro is typically the most shoehorned in of gimmicky control options, the only game I played where I actually appreciated its application over the stick was Wind Waker HD since aiming was a pain otherwise.
Then Kirby Triple Deluxe took things back to the status quo of "nuts to gyro".
But as long as it ain't forced then i'm fine, I just find it particularly bothersome on the 3DS since it conflicts with the whole 3D thing as well as waving around the screen I'm trying to stay focused on in general.
Wait, I actually liked the Gyro in Kirby because you can recalibrate it all the time. Wasn't super-super poop.
I liked it more than some of the gyro in some mobile games I've been playing.