The Dwarves learned of Smaug's death when a talking thrush, alerted by Bilbo to the dragon's weak spot, flew back to the mountain and brought an ancient, wise raven named Roac to translate the news to Thorin and his company, who then celebrated the dragon's demise. Roac confirmed Smaug's slaying but warned them that men and elves were coming for the treasure, ushering in the events leading to the Battle of Five Armies.
He is shot down by an archer named Bard, but not before the dragon destroys the entire town. The men of Lake Town decide to head to the mountain to get some of the treasure Smaug left behind. They will use it to rebuild. Roac tells the dwarves that Smaug is dead.
Birds carry the news of the death of Smaug. The Elvenking comes to the aid of Lake-town and marches north to the Mountain, eleven days after the devastation caused by Smaug.
Thorin was still a youngster (aged c. 24), by Dwarves' reckoning, when the dragon Smaug descended upon the mountain of Erebor in flames. Smaug left the mannish town of Dale in ruins and killed many dwarves who were inside the mountain.
In The Hobbit: The Battle of the Five Armies, Smaug attacks Lake-town. He is killed by Bard with a black arrow and his body falls on the boat carrying the fleeing Master of Lake-town.
It's political, really. Even if Gandalf is powerful enough to go and one-shot Smaug, he would then have created a power vacuum on the edge of Lake-town, and made himself a political figure unable to be directly challenged but ruffling the feathers of everyone nearby.
Bard the Bowman is a character in J. R. R. Tolkien's The Hobbit. A man of Lake-town and a descendant of the ancient Lords of Dale, Bard manages to kill Smaug the dragon, after which he becomes king of Dale.
Fíli (T.A. 2859 – 2941, 82 years old) was one of the thirteen Dwarves who took part in the quest for Erebor, which was Bilbo Baggins's great adventure. He was one of the three Dwarves of Thorin's company who did not survive the Battle of Five Armies (the other two being his uncle Thorin and his brother Kíli.)
After the battle, the Arkenstone was placed by Bard upon Thorin's chest within his tomb deep underneath Erebor, and so was returned to the earth at last.
If Smaug was born in the First Age, he should have been at least 6,212 years old at his death and he wouldn't have been "young and tender" at the falls of the two cities as he said he was.
Why did Fili and Kili have to die? There are a few different theories as to why Tolkien had Fili and Kili die at the end of The Hobbit. One theory is that he was emphasizing the important and loyal role that Fili and Kili had as sister-sons of Thorin, an important relationship in medieval literature.
Smaug: The King Under the Mountain is dead! I took his throne, I ate his people like a wolf among sheep! I kill where I wish, WHEN I wish! My armour is iron, no blade can pierce me!
In Tolkien's lore, even the mightiest dragon fire, like Smaug's, couldn't destroy the One Ring. This is because the Ring was imbued with Sauron's power and could only be unmade in the fires of Mount Doom, where it was forged.
From what I understand, Smaug is a beast that must eat other living things to sustain himself. For example, he does not "eat" gold and jewels, he simply admires and covets them. It's implied that he ate a good deal of dwarves, men, ponies, etc., during his attack on Erebor.
Canonically, Balin is the only dwarf from the The Quest of Erebor that is mentioned as visiting Bilbo after he returns to the Shire but based on the number of mentions of dwarven visitors to him over the years I'm sure a few of the others may have come back West at some point, in addition to other dwarves who knew him ...
There is more in you of good than you know, child of the kindly West. Some courage and some wisdom, blended in measure.
King Thror was beheaded, Thrain fled in despair and was never seen again, and Frerin was killed in battle. The unthinkable had occurred: without anybody realizing the significance of what had happened, the half-elf Thorin had become the de facto heir to Erebor.
Sometime afterward in the coming years before his expedition in TA 2989, Balin would visit Bilbo at least one more time. During this visit to the Shire, Balin met Bilbo's newly adopted heir of Bag End, Frodo, and the young Hobbit would come to learn of some of Balin and his Uncle's travels to the lonely mountain.
Third, it should be noted that Maedhros threw himself into a fiery pit with his Silmaril, while the Arkenstone was found deep within a mountain. Therefore, unless Erebor was of volcanic origin, it is practically impossible for the Arkenstone to be a Silmaril.
Legolas is an elf, so he is immortal. However, he is only immortal in the sense that he will never die of old age or sickness. He can die in battle.
Kili Kili was born in III 2864 in Ered Luin making him 77 years old at the time of the Quest for Erebor. He grew up while the dwarves were mining iron in the Ered Luin. He was the son of Dís and the younger brother of Fili. He was Thorin's nephew.
So he was 36 years old when Frodo was 50. (Human Equivalent of 25 while Frodo was Human Equivalent of 35). That means when Frodo came of age at 33, Merry was 19. And for Hobbits, that means Frodo was Human Equivalent of 18 and Merry probably Human Equivalent of 11 or 12.
At the end of the novel, The Hobbit, Balin has formed such a great relationship with Bilbo that he is the only dwarf to visit him with Gandalf a second time. Later in life, Balin led an expedition to re-colonize the lost dwarven kingdom of Moria.
The main clue is the Hobbits' "coming of age" at 33, due to their extended childhood and adolescence. This would compare to a typical Man coming of age at 18 to 21. Thus, a Hobbit at 50 was a young adult, equivalent to being about 30, maybe 27, in human years.
Legolas's role in The Hobbit films is an addition, as he did not appear in the novel. He is attracted to the non-canon elf-woman Tauriel. In the West End musical, The Lord of the Rings: The Musical, Legolas was portrayed by Michael Rouse.