The R4DS does not have memory, it's only code that enables you to play commercial ROMs on your NDS. You insert the MicroSD into the R4 cart so you can carry around several MicroSD cards and change them instead of having to buy several R4s.
Most roms i download here works fine for me for r4ds well, there are new release such as megaman force and glory days 2 nice!!
Actually there are two M3 cards, Simply and Lite. Simply is a slot 1 solution for NDS and Lite is a slot 2 solution for GBA. The new games work perfectly fine on Simply if you have the latest firmware.
Yes just that, if you wish to discuss it further then create a thread in the Nintendo subforum of the Handheld section.
It's just smaller and has different brightness settings for the screen. Other than that, there are no other differences.
Yes it has a Chinese version as well as English. Just click on the R4DS link and it will expand to reveal download links.
Where do i put the games/nds roms in? Also help come when i start the ds with r4 in it it said couldn't find _ds_menu.dat