Buddhism is not so much agnostic as it is silent (you will find terms such as "suchness" or phrases such as "form is empty, emptiness is form" but that's basically it). It does not spell out the nature of Absolute and is concerned with path to realization only. This alleviates the problem that arises when people searching for Brahman tend to look for it as an object and go in circles chasing various mental images (however, this can be also seen in Buddhism -- even the little it tells about the nature of Absolute can already mislead people in various ways). So, Buddhism leaves it to the seeker to go and see the reality for themselves. I would say, it's the ultimate Advaita.

Advaita Vedanta, on the other hand, has no problem to outline the whole cosmology. And that of course is the main reason why we have all those (mostly incorrect) interpretations (which, I dare to say, Buddha set out to rectify).

I don't remember if I already posted this to you, but in Ramayana there is a part that goes like this:

Once Lord Rama asked Lord Hanuman, “How do you see me?” And Lord Hanuman replied, “When I see myself as a body, then I see myself as your faithful servant. When I see myself as the soul, I see myself as a part of you. And when I see myself as Absolute, you and I, my Lord, are one and the same.”

So, when it comes to the three elements you talk about, what appears as man in waking state, or an incorporeal entity in dream state or deep sleep, is at all times the very Absolute, only mistaken for something else, depending on the mental point of view (thus "seeing" Absolute equals lack of any and all points of view, even though "I-ness" remains).

In other words, the illusory personal self reflects the soul and makes it appear as personal (Atman, jiva) but upon realization it is revealed that there is only one soul and that this soul (which you are) is no other than Brahman or God.

One thing worth mentioning is that realization does not remove the "intuitive dualism" of everyday world and everything that goes with it. It is only seen for what it is from that moment on (you've probably heard the famous saying, "Before enlightenment chop wood, carry water. After enlightenment chop wood, carry water." -- simply, nothing changes, yet everything is different).

Now, as for illusion or Maya -- it's not so much about darkness covering light as it is about absence (or withdrawal) of light. But even that is rather incorrect. There are huge tractates in Advaita Vedanta that try to explain Maya and, while I get what they try to communicate, I must admit that they ultimately fail. Not because of lack of insight, but because (as the same sources correctly add) Maya is inscrutable. That may seem like a cheap cop-out, but it really is that way. You simply really have to see for yourself that the apparent duality (or multiplicity) does not make Absolute dual in any way.