I wish I understood more than a few words of what you wrote. My Tolkien-lore is woefully bad.
To give you a brief summary of the salient facts, from analyses that I've previously written:
In Tolkien's Legendarium the highest power is Eru Iluvatar, the equivalent of god.
He created a race of angelic beings known as the Ainu to aid him in the creation of Arda. Middle-earth is a continent on this planet.
The higher ranking Ainu were named the Valar, the equivalent of Archangels, the less powerful ones were named the Maiar, equivalent of lesser angels. Others existed too, lesser in stature who came to be known as nature spirits.
The origin of all evil in Arda is the most powerful of the Ainu; Melkor, who rebelled against Eru and corrupted Mairon who became known as Sauron and the Fire Spirits which took on the forms of Balrogs. He also engineered the dragons, orcs, wolves etc
During the Second Age after Melkor's banishment, a Council of the Valar was held and it was decided that five Maia in the forms of wizards would go to Middle-earth from Valinor to aid the Peoples of Middle-earth against Sauron who had escaped Melkor's fate.
A list of the key figures:
Eru Iluvatar (god)
Melkor the Rebeller (The most powerful of the angelic beings known as the Ainu, the equivalent of Lucifer)
Kings of the Valar:
Manwë Súlimo, King of the Valar
Ulmo, King of the Sea
Aulë, the Smith
Oromë Aldaron, the Great Rider
Mandos (Námo), Judge of the Dead
Irmo (Lórien), Master of Dreams and Desires
Tulkas Astaldo, Champion of Valinor
Queens of the Valar:
Varda Elentári, Queen of the Stars, wife of Manwë
Yavanna Kementári (Palùrien), Giver of Fruits, wife of Aulë
Nienna, Lady of Mercy
Estë the Gentle
Vairë the Weaver
Vána the Ever-young
Nessa the Dancer
The Maiar that I referenced:
Eönwë (The Herald of Manwë and the mightiest of the Maiar)
Sauron (Melkor's greatest servant and the second Dark Lord)
In terms of providence and free will; Eru grants beings the ability to contribute to the music of creation according to their 'will', if they attempt to alter the cosmic design, seeking creative god like powers they will fail, and no matter how much the rebellious ones blight creation, some unintended good result will occur. These principles apply to all the beings of Arda, from the Ainur to the Hobbits.
Individuals shape their destinies, affect the lives of others and sometimes influence catastrophically the history and even the geography of Arda. But even then, these exercises of free will cannot supersede Eru's ultimate purposes, even if in the short term the cosmic designs can be altered.
Examples:
- Melkor the offspring of Eru's thought had the free will to oppose his creator's intention. But from the discord, Eru begot a new music which resulted is something glorious; Arda's birth. No matter how much Melkor intended to blight Arda, his actions would only give rise to things more wonderful.
- Sauron poisoning the mind of Ar-Pharazon and persuading him to invade the the West, results in a direct intervention by an otherwise remote and distant creator (certainly in comparison to the biblical god), thus destroying the King's followers in a great flood. But the faithful escape to Middle-earth.
- Then in the Third Age, Sauron's ring is destroyed, which results in the renewal of the land and the restoration of the line of Numenorean kings.
It is clear that acts of free will can cause cataclysmic disasters in the temporal, incarnate world, but Eru's ultimate purpose remains unalterable and eternal.
Tolkien described the Valar as 'demiurgic'. Plato used the word demiurge to describe deities who fashion the world and all. The Valar do indeed create the material world of Arda, action that puts them closer to the god of Genesis than to angels. However, there is only one Prime Creator, the One, Eru. Thus, the Ainur and in particular the Valar are sub creators. They participate in the physical making of Arda, but could not have done so had Eru not first given them the theme.
In letter #188 Tolkien stated the following:
"...the whole matter from beginning to end is mainly concerned with the relation of Creation to making and sub creation..."
"...the act of the Will of Eru the One that gives Reality to conceptions, is distinguished from Making, which is permissive."
The etymology of the word:
Demiurge = to divide amongst other possible roots.
The Valar are products of the thoughts of Eru, and as such products are a division of the godhead which actively engages in the skilled work of sub creation, the physical activity of shaping Arda. By being divisions of Eru they are assisting in the further development and division whereby the theme, which is also a product of his thought, is taken from him and shaped by the Valar into the Music and beyond it into the substance of Arda. And finally, they are dividing Arda from Eru, thus assisting in a process of separation through which the One and Arda can contemplate each other. The Valar themselves have subordinates of the same order, but lesser, and thus they are also products of Eru's thought.
And finally turning to Melkor, he was given free will, and great power. Depending on your viewpoint, power doesn't corrupt, it just exposes what was already there. Does that mean that an aspect of Eru was inherently evil? Was Melkor the conduit for that aspect? Was it Tolkien's attempt to create a clear distinction between his own real world views and his work? Certainly. It ties in perfectly with the Manichaean dualism. Good and evil ever opposing each other, even in a creator being, Melkor an outlet for evil, the Valar the outlet for good.
Finally, in terms of the speculation regarding Oromë and Tulkas, well, one can see how easy it would have been for them to simply walk to Mordor and deal with Sauron, but the right to exercise their might was the issue.
Do you think that Talion somehow being revived with wraith-like powers is Mandos' handiwork? I don't see how else this could happen, and the Vala being involved in the plot of this game would be really interesting I think.
Something that is little noticed in the Lord of the Rings is certainly of relevance. While in the Barrow-downs Merry remarkably makes a comment about a past event that he couldn't possibly have any knowledge of regarding a specific event that occurred during the Battle of Fornost. A memory of an individual of Carn Dûm. Now we must ask ourselves, what was the cause of this? Was it the genetic memory concept Tolkien toyed with in other writings? Or was it a case of an individual who died in the area of the Downs, possibly a Dunedan who fell in the war and was buried there. A para-psychological event in which Merry dreams and experiences the actuality of some long ago battle, to relive some unknown individual's last moments to the bitter end.
Now of course this is a mere allusion to such a concept, but one that lends credence to the idea that a being could take hold of another individual. Of course in terms of Talion and Celebrimbor this seems exaggerated beyond Tolkien's allusion to such a phenomenan. To apply Tolkien's thoughts on the continuation of his mythos,
"I would draw some of the great tales in fullness, and leave many only placed in the scheme, and sketched." That he did.
"The cycles should be linked to a majestic whole, and yet leave scope for other minds and hands wielding paint and music and drama." That is certainly what Monolith have seemingly done.
In terms of Mandos and Manwë; Celebrimbor unlike Glorfindel and Finrod for example, was not to be reembodied, but to remain in the Halls of Mandos for a very long time. Thus we must ask, could Celebrimbor have escaped the Halls of Mandos? Absolutely not. No being escaped the judgment of Mandos. Even Melkor was executed at his hands, and his spirit banished in the Void. The next point to consider; could Celebrimbor project his fëa (spirit) via some sort of sorcery? It seems very unlikely that he would possess an ability that he could make use of under Mandos' nose. Finally, if not via deception, what about instruction? Could Talion have been an alternative to the Istari? Instead of placing the fate of Middle-earth solely in the hands of the Istari, the Valar decided to allow Celebrimbor to aid Talion in an attempt to further weaken Sauron's forces. Interesting idea, but it certainly is in opposition to the idea that the Istari were to guide the Peoples of Middle-earth via council rather than brute force. What Talion is doing can only be described as brute force, guided by a lust for revenge.