On #4; I have several trade routes that are going right thru other cities (both city states & rivals) on the way to their destination. It's not needing the other city as a canal, but the shortest route passes right thru the city.
Also, I found another quirk; while icebergs block both units and cargo ships; they don't prevent city connections. (Playing Venice I bribed a coastal city state which was blocked in via icebergs, but the moment it built a Harbor, I got credited with a city connection.)
Also, I found another quirk; while icebergs block both units and cargo ships; they don't prevent city connections. (Playing Venice I bribed a coastal city state which was blocked in via icebergs, but the moment it built a Harbor, I got credited with a city connection.)