I'm pretty sure the only thing that is N3DS-exclusive is the video streaming.NTRCFW (3.4 preview) Can lower the brightness below what you can do normally, but its only for n3ds atm, and has issues of its own. If you only plan on playing like one game before turning it off, and are on an n3ds, that is your best bet.
No. Read the other thread.I'm pretty sure the only thing that is N3DS-exclusive is the video streaming.
It would help you go to sleep, but you'll brick in sleep mode.Fun fact: a N3DS on 2.1 with Power-saving mode enabled does just that.
What? I closed my N3DS several times when I was on 2.1, never bricked.It would help you go to sleep, but you'll brick in sleep mode.