Candy: Hey! Boy, Are you eating a lot of candies? I am asking you a question.

*Candy is used as a name so it should start in capital letter. Punctuation marks are used to show strong feelings or emotions so no need to capitalized the word "hey". When calling a name put a comma after the name then your sentence. Next, the sentence that you used is not in question form, your sentences need to be rephrased.

You:

Correct:

Candy: Because you will have cavities.

*Teeth don't get dirty, they get cavities.

You:

candy:Hey, aren't you the same boy as what my brother the vacumm cleaner?

*The sentences can't be understood. You need to rephrase you sentence.

You:

boy:yeah! your the brother of the vacumm cleaner.

*The vacuum cleaner doesn't have a brother, maybe you mean to say is that the boy who vacuum's has a brother.