I recently watch **The Hobbit: The Desolation of Smaug**. (I already seen all the parts of it)
But from the movie there is a one shot where Bilbo enters into the  Lonely Mountain for finding  Arkenstone and accidentally awakens Smaug. 

Thre is converstion between Bilbo ( here bilbo wear ring) and Sumg (I thing all of you know that shot).  I have a some questions as

 - How dose Smug reconizses it is ring.
 - Did Smug knows about sauron.
 - And how dose Smug knows that darkness is coming. whereas he is sleeping into the cave from many years.

Thanks in advance.