Does Beatty really believe all of the things he tells Montag in the lecture

The answer is yes, he does.

Explanation:

In "Fahrenheit 451", Beatty tries to convince Montag why books are bad. But, there is a paradox. Even though he is a book hater, he is always quoting them in his speech. Just as Montag, he used to be curious about books and questioned the system. Nevertheless, now he considers them to be dangerously informative, in the sense that, books can make someone think beyond their reality and are contradictory. Thus, Beatty really believes everything he says to Montag in spite of being an educated person.

No, he just wants Montag to believe him.