3DS USB cable + Samsung tablet charger works
My cheap 3DS USB cable from eBay works with the N3DS. It's charging. Selling my 2DS, it came with a charger, so I'm selling the charger with it. The USB cable isn't as long as the cable on the AC adapter. Which kind of sucks. Had to move the 3DS.
I put it on top of my router. Don't think the router case gets hot.