[Huinesoron]

Ooh. Well, I think Tolkien mostly thought of Gandalf as a Maia, but there's some really interesting concepts to tease out in that 'mostly'.

To address your second point first, you reference this passage, from an undated document (on the back of the brief 'choosing of the Istari' story, which explicitly has Gandalf talking to Manwe):

Originally Posted by Unfinished Tales: The Istari

Manwë, however, even after the Downfall of Númenor and the breaking of the old world, even in the Third Age when the Blessed Realm had been removed from the "Circles of the World," was still not a mere observer. It is clearly from Valinor that the emissaries came who were called the Istari (or Wizards), and among them Gandalf, who proved to be the director and coordinator both attack and defence.

Who was "Gandalf?" It is said that in later days (when again a shadow of evil arose in the Kingdom) it was believed by many of the "Faithful" of that time that "Gandalf" was the last appearance of Manwë himself, before his final withdrawal to the watchtower of Taniquetil. (That Gandalf said that his name "in the West" had been Olórin was, according to this belief, the adoption of an incognito, a mere by-name.) I do not (of course) know the truth of the matter, and if I did it would be a mistake to be more explicit than Gandalf was. But I think it was not so. Manwë will not descend from the Mountain until Dagor Dagorath, and the coming of the End, when Melkor returns. 8 To the overthrow of Morgoth he sent his herald Eönwë. To the defeat of Sauron would he not then send some lesser (but mighty) spirit of the angelic people, one coëval and equal, doubtless, with Sauron in their beginnings, but not more? Olórin was his name. But of Olórin we shall never know more than he revealed in Gandalf.

Will thou learn the lore / that was long secret
of the Five that came / from a far country?
One only returned. / Others never again
under Men's dominion / Middle-earth shall seek
until Dagor Dagorath / and the Doom cometh.
How hast thou heard it: / the hidden counsel
of the Lord of the West / in the land of Aman?
The long roads are lost / that led thither,
and to mortal Men / Manwë speaks not.
From the West-that-was / a wind bore it
to the sleeper's ear, / in the silences
under night-shadow, / when news is brought
from lands forgotten / and lost ages
over seas of years / to the searching thought.
Not all are forgotten / by the Elder King.
Sauron he saw / at a slow menace ....

To my eye, the most interesting thing about this is the idea of a 'Gandalf cult'. The dating 'in later days (when again a shadow of evil arose in the Kingdom)' means that this is actually a concept associated with The New Shadow! Much like Numenor, Tolkien foresaw the emergence not just of 'a centre of secret Satanistic religion' (Letters 256), but of a 'Faithful' group who mythologised the Elder Days, right down to the War of the Ring.

This even suggests that the poem is in fact a hymn, chanted or sung by the Faithful. Looked at that way, with 'the lore that was long secret' and 'the hidden counsel' sound like a full-on Mystery Religion to me, and the verse actually tells us how the secret lore was received: 'a wind bore it to the sleeper's ear, in the silences under night-shadow, when news is brought... to the searching thought.'

So it's clear that a Numenorean group thought of Gandalf as Manwe, on the basis of dream visions (even if you ignore my wilder surmises). But what if the 'members of their own high order' passage?

Originally Posted by Unfinished Tales: The Istari

For with the consent of Eru they sent members of their own high order, but clad in bodies of as of Men, real and not feigned, but subject to the fears and pains and weariness of earth, able to hunger and thirst and be slain; though because of their noble spirits they did not die, and aged only by the cares and labours of many long years. And this the Valar did, desiring to amend the errors of old, especially that they had attempted to guard and seclude the Eldar by their own might and glory fully revealed; whereas now their emissaries were forbidden to reveal themselves in forms of majesty, or to seek to rule the wills of Men and Elves by open display of power, but coming in shapes weak and humble were bidden to advise and persuade Men and Elves to good, and to seek to unite in love and understanding all those whom Sauron, should he come again, would endeavour to dominate and corrupt.

Of this Order the number is unknown; but of those that came to the North of Middle-earth, where there was most hope (because of the remnant of the Dunedain and of the Eldar that abode there), the chiefs were five.

(Note well the last sentence. Not only were there possibly other messengers 'of their own high order' to different locales, but the Five were only the chiefs of the Istari.)

I can see four possible readings:

1. Tolkien meant the order of the Ainur, not the Valar. Booo-ring!

2. This passage recalls the older version of the Valar, back when the Children of the Valar were still a thing. At that point, there were plenty of Vala-breed folk running around, so sending a handful of them over to Middle-earth wouldn't make a dent. But I think this passage probably post-dates that by decades.

3. 'The Valar' are the canonical fourteen, and the 'chiefs' are five of the Aratar - Manwe, Varda, Aule, Yavanna, Ulmo, Orome, Mandos, Nienna. But which five?
3.1. Saruman has to be Aule. He's the craftsman, there's no real alternative.
3.2. Radagast must be either Orome or Yavanna, the Valar of nature. With Yavanna more focused on plants, I would suspect Orome.
3.3-4. It would make sense for the Blue Wizards, who head off together, to be a natural pair. With Aule already out of the way, that would make them either the sibling group Mandos & Nienna, or the married Manwe & Varda. (Note that, unlike Radagast, there is nothing to indicate that they were male in either this text or LotR - they came as Men, the race, not men, the gender.)
3.5. And Gandalf? As the natural leader, he could well be Manwe - but as the Istar of comfort, he could also be Nienna. Either way, we're left with Yavanna, Ulmo, and either Mandos or Varda holding down the fort at home; I'm most inclined towards the last being Varda, since Mandos has a capable deputy in his wife (making Gandalf Manwe).

4. While Tolkien isn't too terribly sexist, his creations' ideas of authority are. So perhaps 'the chiefs' of the Istari means 'the men', and each was accompanied by his wife? This leads us to a slightly different listing:
4.1. Saruman is still Aule, here accompanied by Yavanna. She may then have gone off to try and find the Entwives. This may explain why Saruman/Aule set up shop near the Ents (so she could find him), but also why he was so angry about them (because they were essentially created to spite him).
4.2. With Yavanna out of the way, Radagast must be Orome, accompanied by Vana. Where would the Lady of Flowers have taken herself off to? The part of Middle-earth most associated with flowers is probably the Vale of Anduin, which has both the Gladden (= iris) Fields and Beorn's bees. It's also right next to Mirkwood, where Radagast/Orome hung out.
4.3-4. The Blue Wizards still need to be a natural pair, and in this case you can't do better than Irmo Lorien and Namo Mandos, the Feanturi themselves. Travelling into Sauronian territory, they're perfectly equipped to influence possible friends of the West (by dreams and visions), and to deal with Sauron's death-cults (like he set up in Numenor). They also take with them Vaire, whose speciality is history - ie, truth, to teach those who have been lied to - and Este, who can bring rest and healing to those faithful to the Valar who are suffering under Sauron's rule.
4.5. Then who is Gandalf? Ulmo has no wife, and would make a decent candidate, except that he's never been shy about revealing his power, and has always preferred to stay out of the Valar's mad schemes. Tulkas we can probably write off. And so, once again, we come round to Gandalf as Manwe, and at his side Varda Elentari, the Elbereth of the elves. While her husband is off talking to the little folk of the world, I imagine her slipping into places like Lorien and Rivendell unseen, simply an elderly woman no-one glances twice at... except that in her wake, the stars seem brighter, and the songs of the elves all the sweeter.

I... didn't actually expect to wind up with Gandalf as Manwe every time; I was assuming based on the name Olorin that he was more likely to be Lorien. But Manwe fits a lot better with the rest of the details, so there we are.

hS