If all western research points seeing a 'going up in a tunnel' during NDE, majority of Eastern say 'going down under the ground' looking
Actually, this is one in the same thing and literally stems from ancient shamanic rites in which (as I believe I've mentioned earlier) one passes through some form of channel or route in order to find the light. In Eastern & Mediterranean regions the common symbolism has been to go down into the earth or, as myth describes, passing through Hades itself. You'll even find inference of this in the Jesus story though it is not part of the official cannon; the lore in which Christ spends his time from his apparent death on the Cross to his resurrection, in Hades/Hell claiming the souls of those that were left behind between Adam and his present. No doubt this is some form of add-on that came well after the whole drama surrounding his actual life and "ministers" needed to glorify the entity even more, but it is part of a familiar theme that goes at least as far back as Babylon. I should point out that many Native American groups also practice this ideology, of going into "the mother" (earth) in order to find answers (when done ritually).
The "up-side-down" descriptions offered through the modern-day Westerner who has strong Judeo-Christian influence in their lives is strictly a matter of personal perspective or I should say "Assumption" because this world looks "UP" to the heavens and as such inserts the idea of going up through a tunnel vs. down through an opening in the earth. Nonetheless, both are passing through a narrow corridor that leads to "the light"
You mentioned earlier the discovery of persons of all types including strangers. . . this is not uncommon in that we all have extended relations with others that are frequently not realized. I can't tell you how many people thank me for helping them who I've never met yet, through my various writings or when I've done talks they attended, my words and experience touch them. I'm not unique in this way, we all have this "echo" as I call it; that famed ripple in the water that moves outward and touches the consciousness of other sentient beings. In your description some of the people found in this NDE situation are "dead", as in "lifeless" in this altered-world; individuals who in life, are actually soulless. If one were to recognize the faces of the dead and meditate on them, it would be found that they are acquaintances that we intuitively know have turned their back on things spiritual and humane; frequently these are people that are self-destructive or "lost" in a more literal sense of things, but many are likewise cruel and manipulative individuals within our own "reality" and how our soul (intuition) perceives them. On many levels this could be seen as a kind of cosmic warning but more than not, it is a cosmic calling; the higher-self showing us the individuals in our lives that we aren't just capable of helping, but karmically obliged to help when it comes to nudging them back on the "right" track when it comes to general consciousness -- humanitarian focus, genuine ethics & morality as well as the assumption of proper responsibility.
Much of this goes back to the rituals that take on the idea of Death, Burial and Rebirth (resurrection), a very common rite found the world over and throughout known time; a very controlled and deliberate NDE type of observance which closely mirrors some of the "Sensory Deprivation" research & techniques popularized in the 1980s (including Rebirthing, though a difference of focus/purpose exists). As a controlled ritual however, one is better able to focus on the vision. . . what your subconscious observations are and what they are saying by way of the intuition. Our suspension when it comes to this type of rite, stifles the logic-side of our thinking (filtering) process so that we are trying to force the in-put to fit a preconceived niche.
Look up Ideomotor Response (a.k.a. Muscle Reading). . . when learning this technique it is paramount to shut down our logical mind and simply go with what the subtle impulses tell us. When the "performer" tries to second guess this in-put he/she will typically fail. This is what happens when it comes to situations such as the NDE styled rituals and even instances of a "Psychic Flash" -- trying to "translate" the various images we are presented; unless the psychic learns to interpret the metaphor each image is trying to communicate the premonition will fail. This is one reason why such things come off as vague and incomplete vs. the solid sense of statement most skeptics demand. But matters of the spirit and even the mind itself (the soul?) will never fit into the standards and boundaries establish by man and our ego, their purpose & form has and will always remain fluid -- grey rather than Black & White.