It's an adjective; "The smallest puppy" is the subject of the sentence as the rest of the sentence describes it. Of course the subject cannot just be "puppy" so it must include "The smallest" as well. Since smallest is an adjective (A word that describes something else,) that answer is Adjective.
Could either be an exclamation mark or just a period. It depends on the context and only so little was given
Dangerous fearful and dark
