It's a traditional Christmas carol that often evokes a sense of winter's cold and the longing for warmth and hope. The lyrics describe a scene of desolation and the anticipation of something better.
Well, without reading the novel, it's hard to say for certain. However, there could be a strong - willed female character who is determined to keep her family alive during the midwinter. And maybe there's an old man who has lived through many midwinters and has a lot of wisdom to share with the younger characters. There might also be a villain - like character who takes advantage of the difficult situation for his own gain.
One of the main themes could be isolation. The 'bleak midwinter' setting often implies a sense of being cut off. Another theme might be introspection as characters in such a desolate environment are likely to look inward. Also, survival could be a theme, both physical in the harsh winter conditions and emotional as they deal with their own demons.
Similar novels to Life in Midwinter included Book of Troubled Times, Spiritual Realm Walker, Tang's Table, King of Familiar, Fairy, Please Listen to My Explanation, and so on. These novels were all completed works and could be recommended for reading Life in Midwinter.
It's hard to say for sure. Sometimes it's difficult to keep track of whether it's on hiatus or not. You could look for announcements from the creators or in relevant comic forums.