Hopefully everything out of Area 51 tbh,
i was thinking 900p at 30fps and base PS4 1080p 60fps...but they have not confirmed 60fps yet. It should not be a big deal to get NNK to 60fps at all though, unless they are trying to consider things like how the animation works. Ghibli has a particular style in the cutscenes at 24fps, and they tried really hard to emulate that style in the real time space. So they might keep it 30fps just so its not as jarring.
There was some small japanese DLC exclusive to Japan, but who knows if they will be bringing that over. You should just expect the same content across all platforms