If I want to run homebrew and/or roms, I only need these, right?

Yeah, I know...lenghty title :)

Anyway, first things first: I'm new around here, and I'm trying to get some advice regarding my DS Lite.

If my research is correct, all you need to run homebrew/DS & GBA roms without flashing the DS Lite is Max Media Launcher and M3 Perfect. Is this correct?

Also, does this method allow you to save the game without any problem? Are there compatibility and/or slowdown issues?

Does this method change anything whatsoever in the DS Lite?
If I want to run an original game, do I just need to remove the Max Media Launcher from the DS Lite?

Just one more question: I'm thinking of getting a 512 Megs Sandisk SD flash card. Is this a good choice?

Sorry for all the questions, and thanks in advance.

That should be fine for running homebrew and backups on your DS.

No it will not modify your DS

the Sandisk 512MB card is a good choice but I would recommend a 1GB High Speed Card for better movie playback and game speeds.