Hey hhidar. I stayed in Niseko with my girlfriend and some Aussie mates for 8 days over new year. Had a massive dump when we arrived, but no snow all week, then another big dump on our last day, bummed!
February had some of the most snow Japan's seen in many years, and right now there's tons of the stuff. This season's been a late winter, but it seems to be lingering around later and it looks like we'll still be getting more snow. Hopefully April won't be so bad when you get there.
On piste the snow is probably the best at Annupuri because it has more Japanese locals and less tourists. Hanazono has the best pipe & park features. Grand Hirafu has the most pistes, but the crowds mean it gets tracked the quickest.
We got a private chalet, but having 5 of us brought the prices down and we had a pretty decent budget for once. It might be a bit much for two people though.
You can get to Niseko via train or bus. The bus is definitely the most convenient as it's a single trip from the airport, about 4000 JPY return. The train requires you to transfer at Sapporo then get another one to Kutchan, then a bus/taxi to Niseko itself. The train can be a f***around if you're coming late and miss a transfer.
You might want to be incognito when going backcountry here, there is a designated slackcountry area at the top of Mt Annupuri, but snow patrol doesn't really like people going under the ropes.