The game will say you can't play it anymore and will give you a link to see what the full version is about. It also gives you a decision whether to delete the demo or not.
Currently, as of this moment, no.
as of right now, no
there is a demo section in the eShop and you can also use the search
No, but they will come out with one :)
you can't. But you can get a demo on nintendo dogs + cats on 3DS
Here: http://3dsmaxtrial.autodesk.com/3dsmax2008trial/Autodesk3dsMax2008_ESD_Trial.exe
You can get the free demo, although that isn't the full game.
Yes, they will cost money unless it is a demo or a limited time event
it clicks
Yes. The DSi, DSiXL, 3DS, and 3DS XL all have the same charger.
It won't fit in a DS or a DSi, there is a tab on the 3DS game to stop it.
The 3DS uses a proprietary battery made specially for it by Nintendo. Therefore the only battery it takes is a 'Nintendo 3DS' rechargable battery.