1) How do I find out people's friends codes?? do i have to know them personally and ask them, or can i play them online then just add them?? How does that whole thing work??

2) If I buy a game used can I erase all that person's previous saves and wi-fi settings for the game??

3) Did I make the right choice in buying the DS over the PSP

4) Which games should I get?? Im thinking Mario Kart DS, Castlevania Dawn of Sorrow and Elite Beat Agents. Are those good choices?? Or should I wait for some upcoming games(if so which are the most hotly anticipated upcoming games)

Thanks guys