Yes, it will.
All DS games work on the NDSi.
No, you cannot play 3DS games on a NDSi or NDS
Yes, they are different. The NDSi games are slightly enhanced and are built mainly with the DSi in mind. Therefore, since the DSi has a better processor, NDsi games generally have better frames per second when played on the Nintendo DSi.
No, only SD cards will fit in the NDSi SD slot
Yes, the NDSi and NDS can connect to play DS games
No, the NDSi cannot play GameBoy games since it does not have the slot 2.
You cannot download MSN for the NDSi
Yes, the NDSi can play games. These include NDS games as well as NDSi enhanced games and DSi ware games. They cannot play GBA games or 3DS games.
If the game is in the form of a DS game card (which most games are and I am pretty sure this game is), then it will work on the all types of the DS, including the DSi XL.In short, YES.
You can purchase Nintendo DSi Points cards in the DSi Shop, accessible on your Nintendo DSi. You can also buy a Nintendo Points Card at any video game store and redeem it for Nintendo DSi Points.
The NDSi does not support Nintendo Zone and can not be downloaded
The 3ds supports all DS, DSI, and 3DS games. Like the DSI, it no longer supports game-paks for the Game Boy Advance.