They connect in exactly the same way as if it were two regular DS.
Yes. The 3DS can play DS multiplayer games with any DS.
Yes
The Nintendo 3DS can connect to the DS from previous platforms but only for games that can be played on the DS or DSi.
yes
No because those games were meant only for 3ds
No, it is a 3DS game, it can only do DS download with another 3DS.
No, the Nintendo DS lite cannot play 3DS games.
The Nintendo DS headset does not work with the 3DS.
There should be no reason why a DS game doesn't work on a 3Ds. I've had mine run several DS games, the only downside is the quality of the image is very poor.
It is called the 3DS XL and it will be released on August 19 2012.
Yes, the 3DS can communicate with other DS systems while playing DS or DSi games or in DS Download Play. However, since the 3DS does not have PictoChat, and no other DS systems can play 3DS software, these features are incompatible.
Yes, but it must be over a WEP encryption or no encryption. Despite the fact the 3DS can connect to WPA2 networks, it is part of the design of DS cartridges that they are restricted to using WEP. So one in a 3DS can't be played online over WPA2, only WEP.