Tolkien's history of Elves singing and Ents walking and talking

Background

Gandalf, when prompting Théoden to get him to understand from his memory who might have brought the forest to fight the Orcs at Helm's Deep, states (bold added):

It is not wizardry, but a power far older ... a power that walked the earth, ere elf sang or hammer rang.

^{The Lord of the Rings, The Two Towers, Book III, Chapter 8: "The Road to Isengard"}

Théoden does not solve the riddle at that time, but eventually learns the power Gandalf speaks of that summoned the forest are the Ents, the Shepherds of the Trees. So Gandalf is stating that the Ents "walked the earth" before (ere) elf sang.

Yet it is the elves that taught the Ents to speak, as Treebeard testifies:

It was the Elves that cured us of dumbness long ago, and that was a great gift the cannot be forgotten

^{The Lord of the Rings, The Two Towers, Book III, Chapter 4: "Treebeard"}

Part of the process of learning to speak appears to be the "old lists" of living things, for

Elves made all the old words: they began it [the list]

It seems that the list is designed to sing, but that may not be so. Still, that Elves were speaking implies they were able also to sing, and circumstantially, it appears that Tolkien's history would flow something like this:

1. Ents were created fully capable of walking and shepherding the forests (having such power as exhibited here to move a forest overnight) prior to ever having speech.


2. Elves were created and thus began to sing.


3. Ents were taught by the Elves to talk.

But in fact, the trees that moved to Helm's Deep were, as Merry testifies in a discussion (bold added):

The Huorns, or so the Ents call them in "short language". Treebeard won't say much about them, but I think they are Ents that have become like trees, at least to look at. ...

   'There is a great power in them, and they seem able to wrap themselves in shadow: it is difficult to see them moving. But they do. They can move very quickly, if they are angry. ... They still have voices, and can speak with the Ents—that is why they are called Hurons, Treebeard says—but they have become queer and wild.

So it could be the power Gandalf referred to that is "ere elf sang," which brought the forest, is the "great power" within the Huorns themselves. Yet Huorns are distinguished from trees in part precisely because "they still have voices," which means they are a creature related to the elves teaching the Ents to speak (whether Huorns are directly related to Ents or not).

This implies a few possible alternate historical orders:

First option

1. Ents were created fully capable of walking and shepherding the forests (having such power as exhibited here to move a forest overnight) prior to ever having speech.


2. Elves were created and could speak, but did not yet sing.


3. Ents were taught by the Elves to talk.



4. Huorns come about, whether from evolving trees that the Ents taught to communicate or from devolving Ents, but they obtain a voice.


5. Elves begin to sing.

Second option

1. Ents and Huorns (whether evolved trees or devolved Ents) were created fully capable of walking prior to either ever having speech.


2. Elves were created and could sing.


3. Ents and Huorns were taught by the Elves to talk or Ents were taught by Elves to talk, and Huorns by the Ents.

Third option

1. Ents and Huorns were created unable to walk (or Ents shepherd) the forests.


2. Elves were created and could speak, but did not yet sing.


3. Ents and Huorns began to walk at the time they were also taught by the Elves to talk.


4. Elves begin to sing.

Questions

So the questions related to all this are:

1. Is it recorded when Elves first sang in Tolkien's history/writings? Did they always sing from first being created or not?



2. How does their being able to sing fit historically in time with the power that brought the forest? That is, which power is Gandalf more directly referring to as being older than Elves singing—the power of the Ents or the power of the Huorns (or is it both, and this is a "proof" text that indeed the "walking" trees are related to one another in some way)?


3. Is it discussed in Tolkien's writings that the Ents (and/or Huorns) did walk prior to ever learning how to speak?

Ultimately all these questions are seeking to figure out what is the proper timeline for Elves singing in respect to Ents (Huorns) walking and talking, and thus was there a period of time in which the Elves talked, but did not sing; and a period of time in which the Ents/Huorns walked, but did not yet talk.

Answer

Ents were likely born at the same time as Elves

Elvish speech and song

The Elves awoke without speech or song:

By the starlit mere of Cuiviénen, Water of Awakening, they rose from the sleep of Ilúvatar; and while they dwelt yet silent by Cuiviénen their eyes beheld first of all things the stars of heaven.

^{The Silmarillion, Of the Coming of the Elves, p. 45}

They developed both before Oromë found them:

Long they dwelt in their first home by the water under stars, and they walked the Earth in wonder; and they began to make speech and to give names to all things that they perceived. Themselves they named the Quendi, signifying those that speak with voices; for as yet they had met no other living things that spoke or sang.

^ibid.

I could not find anything about the order in which they learned speech and singing. I would guess that they developed both concurrently, but I have nothing to support this.

Ents and Elves

Ents awoke at the same time as Elves:

And Manwë said: 'O Kementári, Eru hath spoken, saying: "Do then any of the Valar suppose that I did not hear all the Song, even the least sound of the least voice? Behold! When the Children awake, then the thought of Yavanna will awake also, and it will summon spirits from afar, and they will go among the kelvar and the olvar, and some will dwell therein, and be held in reverence, and their just anger shall be feared."

^{The Silmarillion, Of Aulë and Yavanna, p. 41}

Indeed, Ents were alive at a time when Elves had neither speech nor song.

Ents walking and talking

Ents were able to walk when they awoke. As quoted above:

they will go among the kelvar and the olvar

But also:

"In the mountains the Eagles shall house, and hear the voices of those who call upon us. But in the forests shall walk the Shepherds of the Trees.'

^{The Silmarillion, Of Aulë and Yavanna, p. 41}

As for talking, your quote seems to be satisfactory: although Ents could walk from the moment they awoke, they did not have speech. Elves taught them how to talk and sing.

Huorns

As for Huorns, they seem to be between Ents and trees:

"Some of us are still true Ents, and lively enough in our fashion, but many are growing sleepy, going tree-ish, as you might say. Most of the trees are just trees, of course; but many are half awake. Some are quite wide awake, and a few are, well, ah, well getting Entish."

^{The Lord of the Rings: The Two Towers, Treebeard, p. 77}

I couldn't find any mention of Huorns outside of The Lord of the Rings, so I don't think we'll be able to find a very precise definition. I would guess that Ents were Ents and trees were trees for a long time before Huorns appeared.

I would say they are of a form less mighty than Ents, but more so than trees. I guess you could say they are "devolved Ents" and "evolved trees" (even though evolution has nothing to do with this and "de-evolution" is certainly not a thing anyway).

^{All citations from the Harper Collins editions, all emphasis mine.}