I'm saying that almost all the tasks you describe above also fall under the responsibilities of a good Product Manager (at least on small teams, which is what we're talking about here).
If your "Idea Guy" comes from a Product Management background (and can do all the things you mention above, plus "Strategy"), then you should be in good shape.
If your "Idea Guy" comes from a Product Management background (and can do all the things you mention above, plus "Strategy"), then you should be in good shape.