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 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.
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.
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