It depends if you want to go off site to explore or if you are fine spending the entire time on premise. The restaurants at the PH are good so it's possible, but some people like to explore the surroundings which is not walkable. Everything is a minimum 10-15 min drive.

There is a bus that goes around niseko, but then you are at the mercy of a bus out in the cold.

Left hand driving in the snow shouldn't be an issue for most people. All cars are equipped with AWD and snow tires. You just need an international license.