From what I have found through personal experience is that the "ego" is literally everything sensed by and from physically reality (taste, smell, sight, thought, idea, imagination, feelings, etc). This is all contained in the ego. Ego death is literally a dissolving and letting go of everything you know and everything you think you know. When you achieve ego death, that is when you can really begin to experience. Surrender to everything of your experience so that you can fully experience what you are trying to experience (don't let your brain or mind get in the way of your experience).
As for the "shadow" thing, that sounds to me like what I have come to call, "The Void". A place of nothingness that is everything. Everything there is everything but it is also nothing, but nothing is everything (just a balance from what I have come to think of it as). Everything is a part of you though. Nothing is separate from you. The only thing that separates anything from you, is your own ego.