1.Just go to Niseko. Everyone else does. It's the easiest place to get to.
2.Niseko has a park.
3.It'll be quite expensive. But the Yen is quite weak at the moment, so your Yankee Dollars will go further. It'll be worth it.
There's a load of info on NS, and elsewhere online, but this answers your questions. There are a load of other ski areas in Hokkaido, snowier, cheaper and less crowded than Niseko. But they're not as easy to get to, and find accomodation in etc.
If you have any other specific questions, drop me a message.