The short of it is, there are two devices scheduled for release in the next month, Google's Nexus 7 and the Kindle Fire 2.
Amazon didn't release their Fire in the EU(Or even in Canada!), so I don't know much about how purchases work on the KF, maybe Treat and others could clarify on this. So far as I know, anything that's available for the KF, could also be purchased from Amazon's store using other tablets.
The reason to own an Amazon branded tablet is they give you a neat, seamless interface between your device and the Amazon store - but you are restricted to the Amazon store and locked in to their content.
On another Android device, like a smartphone or tablet, you could still install the Kindle
apps for access to Amazon's content, the same as you would receive it on the Kindle Fire and you have access to everything else out there too. It just takes that extra step of installing these apps.
I don't think you are missing anything from Amazon by not owning a Kindle Fire, but again, an KF owner would need to confirm that.
The Nexus 7 will be running on Android 'Jellybean' (4.1)
Nothing has been announced for the KF2, I expect it will use Android 'Ice Cream Sandwich' (4.0) or Jellybean.
If you want to use emulators, then Nexus 7 is the way to go. With the 1280x800 IPS screen and a Tegra 3 processor, it will be amazing for gaming, movies, reading/browsing.