Timing is excellent Matt - snow will be excellent! Can almost guarantee you some awesome powder.
The Annex is a nice hotel, right in the heart of Akakura Village. You can walk to the lifts easily.
What else is to do depends on what you like. Food and hot springs are two inescapables

Have a look at this site for some ideas perhaps?
http://myoko-nojiri.com/attractions.htm Unfortunately options are a bit more limited in winter. Zenkoji Temple in Nagano City is cool. You could maybe see it on the way through or back.
There's not much nightlife. A couple of cool little bars, karaoke joints, italian restaurant. You could try the beer hall near Ikenotaira. There's a great little okonomiyaki joint in Myoko Kogen itself called 'Yamagishi' but it's impossible to find without someone in the know, plus there's no English spoken.
Head to Jusco/Wing Market in Takada (about one hour) for a big shopping experience. If you go to 'Off House' you can pick up s/h boards super cheap. Buy a couple, take 'em home, then sell them to help pay for your trip

Have a blast!
Cheers, MG