How train/bus/walkable is Fukui Dinosaur museum, Nozawa Onsen, and Obuse?

I'm planning to spend about 10 days between Niigata, Nagano, Fukui (dinosaur museum) and Nozawa Onsen in December.

I know I can train it, but I'm travelling with a 4 year old. Would it make more sense to rent a car(say from Niigata for the round trip) instead of using a train? I don't know how hard it is to drive there or whether Fukui is is just more accessible by car.