DS lite chargers do not fit a 3DS.
It will fit, but it will not work on the Nintendo 3DS
Yes, a Nintendo 3ds is required to play Nintendo 3ds titles. The cartridges themselves will not fit into a DS, DS Lite, DSi, or DSi XL because of a small tab jutting out from the side of each game cartridge.
Yes, regular DS games fit into a 3DS.
Yes, the Nintendo 3DS will play NDS and NDSi games
yes they do
No, the DS lite charger will not fit. You'd need at least the DSi/DSi XL charger which is the same as the 3DS one.
The memory cards are the same, but no, you can't fit a 3DS game into a DSi, it is specially made to not fit, as a DSi cannot run a 3DS game anyway.
The Mask of Miracles will only work with the Nintendo 3DS, the game card does not physically fit into the older Nintendo players.
Yes, you can use ds lite games in the original Nintendo ds. They are not making new specialized games for the Nintendo ds lite. they are still making games that fit both the original DS and the Nintendo DS Lite.
Yes, the 3DS has backwards compatibility to DS and DSi games.
No, you cannot play 3DS games on a NDSi or NDS