It should be noted that Tolkien created three different parallel versions of the Fall of Numenor, each showing a different in-universe way that the story was passed down.
- Mannish tradition - The Drowning of Anadûnê
- Elvish tradition - The Fall of Númenor
- Mixed Dunedanic tradition - Akallabêth
The Drowning of Anadûnê representing "the mannish tradition" is very heavy on Adûnaic names and has a lot of "facts" different from the cosmology shown in The Silmarillion. It can be found in three successive drafts in The History of Middle-earth IX: Sauron Defeated.
The Fall of Númenor represents "the elvish tradition". Unfortunately, of the three texts, this is the most "outdated", as it was last revised during the very early stages of Tolkien's work on LotR. It can be found in three successive drafts in The History of Middle-earth V: The Lost Road and The History of Middle-earth IX: Sauron Defeated.
Akallabêth represents "mixed dunedanic tradition", a mixture of the above two traditions. As Tolkien wrote it, the tale was being transmitted to Ælfwine by Pengolodh, but due to the a late reference in Unfinished Tales to Elendil writing it, Christopher decided to cut out any mentions of Ælfwine. You can find the cut out portions in The History of Middle-earth XII: The Peoples of Middle-earth. I shall be quoting from the original text as Tolkien wrote it.
Let's look at the three events you asked about it in each version of the story:
The fate of Ar-Pharazôn and his army:
The Drowning of Anadûnê:
And who shall tell the tale of their fate? For neither ship nor man of all that host returned ever to the lands of living men. And whether they came in truth to that harbour which of old the Adûnâi [= men] could descry from Menel-Tûbal; or whether they found it not, or came to some other land and there assailed the Avalôi, it is not known. For the world was changed in that time, and the memory of all that went before is unsure and dim.
Among the Nimrî [= elves] only was word preserved of the things that were; of whom the wisest in lore of old have learned this tale. And they say that the fleets of the Adûnâi came indeed to Avallôni in the deeps of the sea, and they encompassed it about; and still all was silent, and doom hung upon a thread. ... Then Amân [= Manwë] called upon Eru, and in that hour the Avalôi laid down the governance of the Earth. But Eru showed forth his power, and he changed the fashion of the world; and a great chasm opened in the sea between Anadûnê and the Deathless Land, and the waters flowed down into it, and the noise and the smoke of those cataracts went up to heaven, and the world was shaken. And into the abyss fell all the fleets of the Adûnâi and were swallowed in oblivion. But the land of Amân and the land of his gift, standing upon either side of the great chasm in the seas, were also destroyed; for their roots were loosened, and they fell and foundered, and they are no more.
The Fall of Númenor:
Into this chasm the Great Sea plunged, and the noise of the falling waters filled all the earth, and the smoke of the cataracts rose above the tops of the everlasting mountains. But all the ships of Numenor that were west of Avallon were drawn down into the abyss, and they were drowned; and Tar-kalion the golden and bright Ilien his queen fell like stars into the dark, and they perished out of all knowledge. But the mortal warriors that had set foot upon the Land of the Gods were buried under fallen hills; there it is said they lie imprisoned in the Caves of the Forgotten until the day of Doom and the Last Battle.
Akallabêth:
But who among Men, Ælfwine, can tell the tale of their fate? For neither ship nor man of all that host returned ever to the lands of the living; and the world was changed in that time, and in Middle-earth the memory of all that went before is dim and unsure. But among the Eldar word has been preserved of the deeds and things that were; and the wisest in lore among them tell this tale, Ælfwine, that I tell now to thee. And they say that the fleets of Ar-Pharazôn came up out of the deeps of the sea and encompassed Avallónë and all the isle of Eressëa, and the Eldar mourned, for the light of the setting sun was cut off by the cloud of the Númenóreans. ... Then Manwë upon the Mountain called upon Ilúvatar, and for that time the Valar laid down their government of the Earth. But Ilúvatar showed forth his power, and he changed the fashion of the world; and a great chasm opened in the sea between Númenor and the Deathless Lands, and the waters flowed down into it, and the noise and smoke of the cataracts went up to heaven, and the world was shaken. And all the fleets of the Númenóreans were drawn down into the abyss, and they were drowned and swallowed up for ever. But Ar-Pharazôn the King and the mortal warriors that had set foot upon the land of Aman were buried under falling hills: there it is said that they lie imprisoned in the Caves of the Forgotten, until the Last Battle and the Day of Doom.
The death of Tar-Míriel
The Drowning of Anadûnê:
And last of all the mounting wave, green and cold and plumed with foam, took to its bosom Ar-Zimrahil the Queen, fairer than silver or ivory or pearls; too late she strove to climb the steep ways of Menel-Tûbal to the holy place, for the waters overtook her, and her cry was lost in the roaring of the wind.
The Fall of Númenor:
But all the ships of Numenor that were west of Avallon were drawn down into the abyss, and they were drowned; and Tar-kalion the golden and bright Ilien his queen fell like stars into the dark, and they perished out of all knowledge.
Akallabêth:
And last of all the mounting wave, green and cold and plumed with foam, climbing over the land, took to its bosom Tar-Míriel the Queen, fairer than silver or ivory or pearls. Too late she strove to ascend the steep ways of the Meneltarma to the holy place; for the waters overtook her, and her cry was lost in the roaring of the wind.
Sauron's glee
The Drowning of Anadûnê:
And it is said that Zigûr [= Sauron] himself was filled with dread at the fury of the wrath of the Avalôi and the doom that Eru wrought; for it was greater far than aught that he had looked for, hoping only for the death of the Adûnâi and the defeat of their proud king. And Zigûr sitting in his black seat in the midst of his temple laughed when he heard the trumpets of Ar-Pharazôn sounding for battle; and again he laughed when he heard the thunder of the storm; and a third time, even as he laughed at his own thought (thinking what he would now do in the world, being rid of the Eruhîn for ever), he was taken in the midst of his mirth and his seat and his temple fell into the abyss.
The Fall of Númenor:
N / A
Akallabêth:
For Sauron himself was filled with great fear at the wrath of the Valar, and the doom that Eru laid upon sea and land. It was greater far than aught he had looked for, hoping only for the death of the Númenóreans and the defeat of their proud king. And Sauron, sitting in his black seat in the midst of the Temple, had laughed when he heard the trumpets of Ar-Pharazôn sounding for battle; and again he had laughed when he heard the thunder of the storm; and a third time, even as he laughed at his own thought, thinking what he would do now in the world, being rid of the Edain for ever, he was taken in the midst of his mirth, and his seat and his temple fell into the abyss.
So to answer your specific questions:
The fate of Ar-Pharazôn and his army was known to the elves of Tol Eressëa, and from them to their elven brethren. The story is told directly in the elvish tradition, but the other two traditions don't know it themselves and just add "and this what the elves say happened".
The death of Tar-Míriel and Sauron's glee only appear in the mannish/mixed versions. They were likely an embellishment made for the story.
