how do the townspeople react to the initial warnings from the bard?

The town really can't do much against Smaug. I don't recall Bard actually warning them of anything. Bard eventually kills Smaug by shooting an arrow into his weak spot. Once the dragon is dead, there is a free for all for the treasure. Bard is declared King but it is the master of Laketown who informs the people of the problem of the Dwarves. I'm not too sure if you are referring to something different. Please let me know if you are.