1) I doubt the Kindle will be available outside the US anytime soon.
2) If you need to purchase from the SonyStore, you'll need to run the Sony software under Windows emulation, while if you want to reflash your device when there's a future firmware upgrade, you'll likely need to re-boot into Windows. On the other hand, for normal day-to-day usage & device management, there's the cross-platform (Python)
libprs500 app that means that the Sony works fine with Macs.