A gossip magazine and some beauty aids
Antecedent of a pronoun is a word that the pronoun refers to, or replaces. So, in this sentence, we are looking for the antecedent of the pronoun IT. The pronoun IT replaces the noun Chicago, which means that the word Chicago is the antecedent of the pronoun IT.
IT provides the best opportunity, meaning that Chicago does that.
No, because as you said it "does NOT contain fact-based details" therefore it is not reliable. If something doesn't contain fact-based details, it isn't reliable.