The only difference is the one from Best Buy will have a US style wall plug adapter that the USB cable can plug into while the one ordered from Amazon to Sweden will just have the USB cable but no plug adapter. (at least that's how ith works with the K3)
According to the website... yes. The plug would be useless without some kind of adaptor anyway. Plenty of cheap adaptors available on Ebay though. Not sure if there would be warranty issues, or if the 3G would work. From what I read 3G should work everywhere there is coverage?