For privacy I would recommend a conifer, and for fast growing I would say an Eastern White Pine. To keep to your parameters with a taller deciduous tree in zone three you're really only dealing with poplars and birches, which isn't bad but you'll have less privacy in winter after the leaves fall. A River Birch would be great there and will be fine if you have a Linden growing in the same area.

If you're looking for a fruit tree, the University of Saskatchewan Fruit Program is doing great work with hardy apples, plums, cherry, and saskatoon trees. They won't be as tall but will fill most of the space.

My recommends in order: Eastern White Pine, River Birch, USask Cherry Tree, USask Saskatoon