>>25002757no, just re-download the game from the eShop for free once you're done with the transfer
Craigslist is pretty straight forward, post your item for sale with a price, description of item and some pictures. You can choose to be contacted via email or phone (either call or text); phone is a lot quicker though. Once you come to a deal with someone, either choose to meet the person in a well lit, busy, public place (if you're in a sketch neighborhood, this is perfect for you) or have them come to your house (don't let them in, just have them call you when they arrive and do the exchange outside).
I don't live in the most safest of places (San Bernardino) but I've never had an issue using Craigslist. If you're still not comfortable with meeting up at a public place, take a friend with you just in case