yes you do without the memory card you cant save games you play
R4i card is a slot-1 flashcard, it can only play DS and DSi games. M3i Zero is a multi-media flashcard, it not only can play DSi games, but also powerfull in multi-media play. M3i zero card can also play GBA games.
You can't
Yes. It depends on the game you have. On the back of the game case it says Download play or Multi card play or both.
yes you could battle in multi card download play too yes you could battle in multi card download play too
There are lots of games that you can play without downloading, and they don't require graphics card. You can find some here: Pituligames.com
Only if you have downloaded it on your Memory Card.
I prefer the the sports games that are multi player games. All sports games are multi player and the call of dutys and such are all multi player games.
There are many ways to play games without a computer. Such as using an iPad, iPod touch, your smartphone, board games, card games, etc. . . If you don't have any of those for some reason, you can just go outside and play.
The DS generally needs no accessories to play games, other than the guitar hero add-on.
No, all games require graphics cards to play.
You cannot play any sound without a sound card.