Yes
Yes you can!
Well, any game that you can buy on the DSi store is not a DS game, such as "The Minis March Again." There is a DSi-only game which requires the camera to play, it is called Monster Finder and cannot be played on a regular DS (though it should work fine on a DSi).
Yes. It is a DS game, with DSi-enhancements. Because of this, the game is region-locked when played on a DSi, DSi XL or 3DS. This does not apply when playing on a DS or DS Lite.
no
The DSi doesn't have a gameboy slot, so GB, GBC or GBA games can't be played on it at all.
The following comes with a DSI XL: wrist strap, cleaning cloth, manual, and the downloaded games DSI Music, DSI Camera, Pictochat, Flipnote Studio, DS Download Play, Brain Age Express: Math, and Brain Age Express: Arts and Letters. Some special packs include a game, but that isn't to common.
Yes it can.
It is a DSi-enhanced game which plays normally on the DS and DS lite, as well as with additional features when played on the DSi and 3DS, and their XL versions.
It has a built in camara, MP3 player, web browser, Brain Age Math and Brain Age Reading, Flipnote studio, you can buy games without a game card that go directly onto your DSi, and basiclly everything a DS has. The only difference is it has no Game Boy compatibility.
yes, the dsi hasn't changed the game slot so any ds game works Addendum: ACTUALLY... Guitar hero cannot be played on DSI, you need the gba slot for the finger pad
its a game system that u can play and has brain age and 93% wide screen and has a photo clock
3DS games can only be played on the Nintendo 3DS(XL) and 2DS. Therefore, Nintendo DS and DSi cannot play 3DS games