When I teach Adult Lay Formation classes, I always get questions along these lines: "Father, how did X happen?" Or "Why did the Church start doing Y?"
I am challenged in answering these question by the fact that the answers are usually highly complicated and would require a couple of hours of explanation.
Why a couple of hours?
Because our faith (liturgy, canon law, theology, philosophy, etc.) are all intertwined. . .every question about X is rooted in several additional questions about A, B, C. . .W.
For example, "Why did the Church move the priest behind the altar to face the congregation after VC2?" I can't even begin to answer this question thoroughly until it's clear why the priest faced liturgical East in the first place. . .why we consider the Mass a sacrifice. . .the role of the priest in sacrifice. . .the move toward liturgical egalitarianism post VC2. . .etc.
One way for the laity to better prepare themselves as teachers and preachers is to read Robert Royal's latest book, A Deeper Vision: The Catholic Intellectual Tradition in the Twentieth Century.
What you get in this excellent book is an overview of how the Church thought about her faith from the late 19th century to the pontificate of Pope Benedict XVI.
Some of the chapters will be tough going for regular Catholics (i.e., 99.99% of Catholics who don't spend their lives as academic theologians and philosophers). For example, he covers Rahner, von Balthasar, Ratzinger, and several other modern European theologians.
The chapter on the intellectual challenges and reforms of VC2 is spot on. He explores the major documents in some detail and covers the more controversial aspects of others. He's balanced here, but it is abundantly clear that he does not believe that the Council has been fully or properly implemented.
The second half of the book is probably the most important for the laity in that it places the intellectual life (not just the academic life) of the Church squarely in the public sphere, challenging the laity to take up their charge to evangelize our secular culture.