The 3DS has its own library of games, but can also play any games released on the DS or DSi.
You buy ds or 3ds games and then put them in your 3ds.
Yes, but the 3DS does not
Yes, you can. The 3DS can link with the DS to play DS games but the DS cannot play 3DS games so linking for 3D games will not work.
Yes, you can play DS games on 3DS, but you can't play 3DS games on DS.
Yes, the 3DS can play 3DS games that cannot be played on the DS or DSi
A 3DS can play DS and DSi games, but not in 3D.
No, you can't download retail DS games on the 3DS eStore.
No the 3DS game cards are shaped slightly different then the Nintendo Ds. Of course if you could put the 3DS game cards in the Ds lite it would still not work because the features and intense graphics the nintendo 3DS requires for games can't be used on the Ds lite. Don't buy 3DS games for the Ds lite as it just won't work. You can consider buying a 3DS however as the 3DS is backwards compatible with all DS games.
DS games can be played on the 3DS but 3DS games can't be played on the DS.
because the 3d games are only built for the 3ds but the ds games will work on the 3ds but they won't be in 3d