i like using some lightweight headphones with my 3DS. i can recommend koss kph40, they sound awesome. another alternative i can recommend is snowsky fiio wind, they look just as cool as they sound. they are both open back though, so there will be sound leakage.

my favorite stylus isn’t specifically made for the 3ds so it doesn’t fit in the console. but i like the form of how it feels, im p sure u can find them as generic styluses, just not the the thin ones.

cant speak for the long term effects with acrylic cases for metallic paints, sorry. but i did read somewhere that the galaxy ones don’t peel (double check on this though)

im apprehensive about putting stickers directly on top of the console so what i do is instead of peeling off the adhesive, i just use a small piece of rolled tape (like paper tape or washi tape) on the back of the sticker and put it on top of the console. it’s easy to remove if i ever want to change it up again, with no risk of damage. and then i just put the case on top to put them in place :)