heavy. The tyres are heavy, the frame itself is heavy and the accessories are heavy. if it's not hitting at least 15kg you're under equipped.
average speed is useless since this depends on how clean the road is... if any pavement can be seen at all. and the shoveling and plowing is never uniform.
it takes roughly 3~4hrs for a 50km ride on unplowed roads with slightly poor equipment choice.
by poor equipment choice I mean tyres that are not fat enough and fenders that allow snow-ice build up.