1) Check Gateway's official retailer list from their website.
2) Depends, do you have a 3DS that GW supports?
3) The USA N3DS probably will be above 9.2, and thus won't be supported. Maybe GW will have later support by then, but unlikely.
4) We don't know yet, since there aren't any N3DS exclusives, but probably.
5) GW doesn't do emulation.

 

Nope, there's no emulation going on in there, just file system redirection. But on-topic, the Gateway itself emulates nothing and plays nothing but 3DS ROMs. However, there are a few emulators (in the form of 3DS ROMs) for SNES and the like. However, if all you're looking for in that department is regular DS ROMs, Gateway sells two cards together, one for 3DS ROMs and one for DS ROMs. That said, the DS one currently doesn't work in the latest firmware (it's designed to run in the 4.5 3DSs that can run the 3DS card as well) and doesn't appear to be updateable, but only time will tell.

 

1) Doesn't really matter, just order from a place that ships from your country.
2) Good; hold onto that system.
5) Emulation has nothing to do with it. It runs the ROMs natively on the 3DS system. Emulation typically involves dynamic recompilation of other platform's code.