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.