Is all this teaching about the Da Vinci Code worth the effort?


Obviously I believe it is. But not without consideration. It does feel quite silly to have to say, "This fiction book is not true". Yet, clearly the da Vinci Code is leading many believers astray, and it is threatening the beginnings of the faith journey for others.
Beyond that, it provides an opprotunity not only to engage the culture in a way that matters but it also provides a chanel for needed but often ignored teaching concerning Church History. Suddenly people are truly interested in the history
of their faith. I consider it a bonus.
As Irenaeus (see below) grudgingly picked up pen to elucidate gnosticism in order to protect the "simple ones" and in so doing enriches us yet today with a new comprehension of 1 John's anti-Gnostic bent — so to we must answer the problems of our day as best we may and entrust the results of our labors to the Father.
"Inasmuch as certain men have set the truth aside, and bring in lying words
and vain genealogies, which, as the apostle says, “minister questions
rather than godly edifying which is in faith,” and by means of their
craftily-constructed plausibilities draw away the minds of the
inexperienced and take them captive, [I have felt constrained, my dear
friend, to compose the following treatise in order to expose and counteract
their machinations.] These men falsify the oracles of God, and prove
themselves evil interpreters of the good word of revelation. They also
overthrow the faith of many, by drawing them away, under a pretence of
[superior] knowledge, from Him who rounded and adorned the universe; as if,
forsooth, they had something more excellent and sublime to reveal, than
that God who created the heaven and the earth, and all things that are
therein. By means of specious and plausible words, they cunningly allure
the simple-minded to inquire into their system; but they nevertheless
clumsily destroy them, while they initiate them into their blasphemous and
impious opinions respecting the Demiurge; and these simple ones are
unable, even in such a matter, to distinguish falsehood from truth."
Irenaeus Against Heresies 1:1