Amazon App Store works fine for out of North American customers as long as you have a US address (and probably credit card with the same address) on file with them and make that your current address. I have no problems using the AAS from Korea with my parent's address from the US. I also ran into this kind of problem when downloading free books from Amazon. It was free with a US address but $2 with my Korean address. I guess it costs more to send things further on the interwebz.
I noticed the lack of info on the actual download page on device requirements, too. But the info is there on the main app description page.
The free version of Angry Birds Amazon is giving away (Rio I think) does run on my Edge. A little slow, but it does run. Okay, a lot slow.