Yes, the 3DS has backwards compatibility to DS and DSi games.
DS lite chargers do not fit a 3DS.
The DS lite is almost exactly the same size as the 3DS.
3DS games cannot be played on a DS lite. You need a console from the 3DS family - 3DS, 3DS XL, 2DS, New 3DS, New 3DS XL.
As of February 2014, there are 7 versions of the DS. DS and DS lite DSi and DSi XL 3DS, 3DS XL and 2DS
Yes the 3DS and DS lite are the same size
No, the Nintendo DS lite cannot play 3DS games.
Yes it is a Smaller Version of the original Nintendo DS the only other DS that is a totally new ds is the 3ds although Dsi supports dsi titles that the original and lite versions do not but the 3ds supports all of them. You can also play ds Games on a 3ds but you cannot play gameboy advanced games on a 3ds whereas on normal or lite ds you can play Game Boy advanced games.
Yes It works on the DS Lite, DSi, and 3DS.
From what I know, no. The 3DS games have a something on the game card that doesn't let you put it in on other DS systems. To play Animal Crossing 3DS, you would need to buy a 3DS.