@siawgu, for starters, this isn't the right place to ask. This is to post in NDS games that you own (And no, no pirated roms allowed). Bring further questions to the FAQ ok?

To answer, what do you mean by sleeping? is it on standby mode after you turn it on? Or complete off? If complete off, don't leave it more than 2 months, or you would need to recharge it again.

To browse the Internet, you would need to purchase the NDS Browser and also RAM pack. For MP3, I believe DS Vision, a cart from Nintendo can do the trick for u.

Yup. Sleep mode is to just close the lid during anytime in the game. It also makes the Power light blink, indicating it is in sleep mode.

No problem. Check out the list in the first page done by bidfordun. Other recommended games are also listed in the Faq for DS area. it really depends on what genre of gaming you like. And there's a whole lot of RPGs in this platform.