Am I correct in saying there also won't be a wake separation requirement if there are two departures from opposite runway ends? Reason being that we'll rotate past the point on the runway where they rotated.
Well, the ac does not generate wake until after rotation, and out of ground effect. It would be unlikely that even if rotation points were before each other, that a wake would be encountered. I do not see any reference to this scenario as it is a bit unusual to have simultaneous DEP operations. Must play hell with the ILS for the arr.
In your other examples, are runways parallel of perpendicular to each other?