Smaug tells Bilbo not to trust dwarves:
In return for the excellent meal [of the Company's ponies] I will give you one piece of advice for your good: don't have more to do with dwarves than you can help!
Smaug-The Hobbit: "Inside Information"
Smaug has never smelled anything like Bilbo and he cannot place it.
He says they want revenge.
It was his smell. Smaug had never encountered a hobbit before. He did not recognize the smell of him, but could tell that he had been with the dwarves.
No, Bilbo did not kill Smaug. In the novel and movie adaptations, Smaug is killed by Bard the Bowman.
After he gets away from Smaug, Bilbo makes up a saying that would become a favorite of his. Never laugh at live dragons, Bilbo, you fool.
because he tells smaug he is Barrel-rider
Smaug knows the smell of men and dwarves, but is unfamiliar with the scent of Hobbit.
Bilbo told Smaug a riddle to keep him distracted.
The GLOW of Smaug!
I believe it was Roac.
He retrieves it when he is escaping Smaug
Yes, he could and he held a long conversation with Bilbo. Bilbo unknowingly gave a lot of information that he shouldn't have and Smaug revealed a weakness.
He gets the dragon to brag about his jewel encrusted chest. When Smaug shows it off, Bilbo sees the unprotected spot.
Fictional. Bilbo says this to impress and confuse Smaug.
A necklace of emeralds from the treasure of Smaug.
Bilbo doesn't want to give Smaug his name for fear of evil spells, but he also doesn't want to refuse Smaug's request for fear of angering the dragon.
Bilbo snuck in very quietly and grabbed the cup while Smaug was asleep.
Bilbo was warned by the Elvenking about treasure hunting and the dangers of Smaug.
Smaug doesn't recognize the scent of Hobbit, although he knows what dwarves and men smell like.
Bilbo was hired by Thorin and his party of dwarves. They went to the Lonely Mountain. There Bilbo helped them retrieve their treasure from the dragon Smaug.
Yes AND no. Yes because when Thorin, Bilbo and the others went into his lair, he deliberately laid on his stomach on his treasure. Why else; to defend this weak spot! No because he forgot. Bilbo tricked Smaug twice into revealing it. The first was during his conversation with Bilbo. Smaug was very polite with Bilbo listening to his riddles. Convinced that Bilbo did not mean him any harm, Smaug rolled over on his back. Bilbo saw the spot where the scale was missing somewhere on Smaug's chest. The second time was when Smaug realised that Bilbo ran away with a golden two handled cup. This pushed Smaug's infuriation to its boiling point. He started destroying things and eating the dwarfs ponies and when he got to Long Lake, he was flying so high that the chink in Smaug's armor was visible. Bard the Bowman shot him in that very spot, Smaug didn't see it coming.
In the beginning it was Smaug , then in the end of The Hobbit , Bilbo gains it