like lightsabers
Reminds me of the Jedi KotC I started to create a while back.
Baking Pizza doesn't even require much technology. A good oven, preferably wood burning, and you're good to go. Granted, even fire can behave weirdly in the NN, but as a primal force, it should be relatively stable except for the weirdest parts of the NN.
A lot of things would probably work for a while. I think it is sort of like hexing (albeit not exactly). The older it is, the more reliant it will be. A windup clock would still work, when an electrical one is already showing treehouse past cinnamon o'clock.
The closer the region of the nevernever is to the mortal realm, the more it is probably bound to follow the mortal realms natural laws. Not always, but I would use that as a rule of thumb.
There's also a difference between not working and working in a weird way. A gun could stop working, because the area you are in doesn't allow for explosions. Or an explosion could result in turning any metal it touches into chocolate pudding.
Regarding the "everything exists" thing, I would think that's only sort of true. I think a lot of things from mythology are the same thing from the nevernever, only with different names attached to it, depending on the culture it comes from. I like this for two reasons. One, it makes things easier, by reducing the number of things that actually have to exist. Two, it allows for some really nice twisting of existing mythology, and that's something I love to do.