Two interesting things - how long the crow lives and where they nest. I now have an idea of where to look for them. Being at the center top of a tree and the crow's nest on sailing ships, how things are named is always interesting.
Grackle's eye color is a distinguishing marker as is the color of some of the grackles. To me they look sort of doofus when walking. Coloring: brown-headed blackbird is sort of easy, and the red-wing blackbird is easy (they're also smaller than a crow). Ravens seem to be scruffier and in some of the pictures they looked "oiled".
In regards to #1, I would point out that snakes and squirrels are the biggest danger to songbird nestlings than crows.
To answer #2, I go back to the 60's after graduating from high school. I went rabbit hunting with a friend in east central Missouri. We were walking through a large field with forest on either side of it. We saw two crows heading for us and then veer around us just out side of shotgun range. I always thought that was amazing and have since then always considered crows intelligent.