I think they start offering next season booking deals around August. Maybe earlier.
There is a new village at the base of Winterpark. Lots of accommodations there. That is where you want to stay. Check with Amtrack, they may not have baggage fees. Not sure if that has trickled down to trains or not. During the season, a free bus service runs up and down the valley.
Mount you stance back is all you need for powder.
Now for the downer. Having lived in Colorado for 24 years now, and Winterpark is probably my favorite front range area. NOAA is calling for an El Nino year. Pretty much every past El Nino has sucked for I70 corridor resorts. Sometimes the spring is awesome. Sometimes it is just one month that is good. In 98 the only good month was January. Then it snowed like hell after the resort closed. Areas in the Southern part of the state tend to do better during these seasons. Telluride, Silverton, Crested Butte.
Now there have been good El Nino years too. 6 or 7 years ago was a great one and Winterpark-Berthoud Pass did great. So it is not always bad. I would try to make sure you have an acceptable cancellation policy for your trip just in case is all. I guess that is true for any year.
Time of year to book for? March is usually the snowiest month and the temps are not as cold as in January. Much more mild. Last week or two of February can be really good and so can the first week of April. Bonus for April, the crowds go way down.
Hope that helps.