Daisetsu Sounkyo in February

I am planning a trip to Japan hopefully to coincide with the Sapporo snow festival next year (2009). I thought it would nice to stay in Sounkyo while they have the ice festival.

My first question is: Is Sounkyo likely to be incredibly busy at this time of year? I've heard from various friends that if you plan on staying in Sapporo over the snow festival you really need start preparing very early in order to get a hotel and such. Is Sounkyo likely to be the same? Am I leaving it too late already if I want to organize a trip there?

My rough plan at the moment is:
Fly into Chitose Airport. Travel to Sounkyo. Stay for a few days and then Head to Sapporo and spend the day enjoying the snow festival there before catching the Hokutosei Night train from Sapporo to Tokyo.

Does this sound sane? Assuming it does it does has anyone else been to Sounkyo at this time year? Anything to recommend?

Also the Hokutosei train: I've been reading some older posts which mention there is more than one Hokutosei each day. Ideally I would like leave later rather than earlier (I remember mention of train leaving Sapporo around 7:00pm) To get a bit more time in Sapporo. However all posts mentioning the later trains are a year or more old and as far as I can tell from the website (http://www.jreast.co.jp/cassiopeia/hokutosei/time.html#a1) there is now only one train? Is this correct?
Another quick question on busyness, is the Hokutosei likely to be very busy at this time of year? I gather you can only book a place once you've arrived in Japan so I would only be able to book a few days in advance.

Any thoughts and comments would be most welcome.

Thank you.

I have not been to Sounkyo in winter and can't judge.

Also the Hokutosei train: I've been reading some older posts which mention there is more than one Hokutosei each day.

Since 2008, there is only one train per night in each direction on regular nights. It leaves Sapporo at 17:12. During peak seasons, there might be additional trains.

Another quick question on busyness, is the Hokutosei likely to be very busy at this time of year?

It is likely to be very busy during the snow festival, especially on weekends.

Since 2008, there is only one train per night in each direction on regular nights. It leaves Sapporo at 17:12. During peak seasons, there might be additional trains.
Ah, that makes sense. If it is possible there might be additional trains where would I find out about them?

It is likely to be very busy during the snow festival, especially on weekends.
I thought that might be the case. We shouldn't be travelling at the weekend at least (probably on a Tuesday or Wednesday). What do people think are the chances of being able to book and get a place 3 or 4 days in advance?