Unless you have a Japanese 3DS, you can not change to a Japanese region.
Yes, the Nintendo 3ds has is on cards, but how ever the Nintendo 3ds is able to play normal DS games
No, 3DS games can only be played on a 3DS.
It has master quest, which is a mirrored, more difficult version of the normal game
Yes, they play normal DS games, and the 3DS has a camera, so it can.
Around the same size as the normal ds are!
No ones sure yet, but the price should drop a couple of bucks near Christmas time hope this helps =) the 3ds price will change to 170 at august 12 2011
Of course. The 3DS XL is just bigger. It can still play normal DS and 3DS games.
yes There is the origional for the GameCube and Ocarina of Time 3D for the 3DS
No, it cannot.
yes
No you have to have a 3ds