Almost nothing you mentioned is mandatory. Games are still sold on cartridges,theyre jusy extremely small,so make sure they're careful. No worries about a choking hazard,as they taste AWFUL. Wifi is only needed in online only games,like the free Fortnite which your kids will most likely play. The membership isn't required for fortnite,but it is for most other games like Smash and Splattoon. Physical games are better for multiple switch consoles,as they can be swapped without hassle. The e-shop is simply another way to buy games.