Gerres,
For ASME Y14.5-2009, I don't think it is correct to apply "profile of a line" to an edge. As I understand it, the tolerance is meant to apply to line elements extracted from surfaces.
Whether datum features exist and are referenced by the profile tolerance should be based on functional requirements.
I don't think there's any difference between specifying "profile of a surface" with a general note or with an "all over" leader.
pylfrm