Hi bitbit,
Just a couple thoughts. Eastern hemlock can be a shrub or a tree, depending on the variety. It can tolerate shade and deer leave it alone. And I don't know if you specifically want a dogwood tree rather than a shrub, but one of my favorite dogwoods is Ivory Halo which is fairly compact. I have a mixed shrub/flower border in the front of my house with small weigela (Tango), yew, dogwood, birchleaf spirea, hydrangea, and flowers mixed in. Since I don't have deer here I'm not sure if they would bother any of these shrubs. The flowers are sedum, candytuft, knautia, phlox, boltonia, coreopsis, dianthus, daylilies, and a few lilies. I do have a few bulbs mixed in but lose many of them to rabbits and squirrels. I know deer like lilies, but I'm not sure about the rest. Seems like they would have to be pretty bold to bother the area right in front bordered by the sidewalk...but I know my friends who have deer around say they can get to anything if they are hungry enough.
