This one is... surprisingly difficult to answer. You see, there's definitely a medieval commonplace going all the way back to Pope Gregory the Great (r. 590 - 604) that pictures are the "books of the illiterate." The phrase eventually shifts to "books of the laity" and becomes a commonplace. Do these images teach? It's rather more likely that they're going to be there to remind people of what they already know.

Now then, in some cases, there are areas that we're pretty sure that laypeople "got" what the pictures meant. Your average Christian layperson would at least be familiar with the basic Bible stories (although they wouldn't have called them Bible stories), and by the time we get to the twelfth and thirteenth centuries, there's an effort to make sure that all Christians, whether lay or clerical, have at least a baseline of knowledge of the Christian religion, even if that's just the ability to rattle off (or stumble through) the Apostles' Creed, the Lord's Prayer, and the Hail Mary.

But most medieval knowledge of Christianity wasn't really book-learned except for the small percentage that was ordained clergy or literate laypeople. How would they have learned their teachings of Christianity? There's definitely a sense that godparents should teach their godchildren the Creed, and there's also a sense that one's parents are responsible for basic religious formation. After all, in the Arthurian story Perceval, there's the charming story of young Perceval who's been raised in isolation from anything to do with knights, and when the young lad first sees a knight he thinks the knight is an angel, and so he drops on his knees and recites, "his entire Creed that his mother had taught him." You may also have had priests teach children in groups -- or at least you have directives that this be done in some English dioceses.

There would also be preaching. We read in the canonist Durand that although it's not often listed in the liturgies, by the late thirteenth century it was customary to have a sermon between the reading of the Gospel and the offertory, at least occasionally (although we shouldn't assume weekly preaching, at least not by your average parish priest). Usually that would amount to just translating the day's reading from Latin in English, French, German, Welsh, etc., sometimes with a little bit of the priest's own commentary. Sometimes it might be a well-composed sermon, but that was probably more of a rarity.

And then there's the liturgy. The liturgy itself is the sort of thing that would often re-enact and embody scripture, especially at key moments in salvation history. We can see from surviving sermons that clergy often used the Palm Sunday procession as a way of teaching the story of Christ's triumphal entry. For Easter, you'd take a host and deposit it under the altar on Good Friday and then bring it back up on Easter to represent Christ's death and resurrection.

From the thirteenth century on, in more urban areas you'd also have plays that acted this stuff out.

So especially for something like events in the life of Christ, you'd see the wall paintings in a Church and you'd have an idea where they fit into the stock of stories you know. In fact, they'd often move down the nave -- of a parish church -- from the entrance to the altar, where you'd see the crucified Christ, and so the right-to-left procession would give you a sense of Christ's life culminating in His death and resurrection.

Okay, now, to bring this back to your question about a Cathedral like Chartres.

First thing to note is that while for some people the Cathedral Church would double as their parish church, very often your layperson, even in a city where a bishop had his see, would go to church at the parish church just down the block. So the people in a church like the cathedral will be a good chunk of the illiterate laypeople, but also elites, who can read and will know their Bible.

And here's where things get weird. We know that a layperson at his or her parish church will understand an image of the life of Christ, the Holy Family, and the various Saints. They'd probably know that the image on the rood screen of each Apostle holding a scroll with a clause of the Apostles' Creed represented the Creed.

But what about more symbolically complex art, like the Tree of Jesse representing the lineage of David? You can't really figure that out, and you're not really going to see something that complicated in a medieval sermon to laypeople. That's where things get weird. We know that your religious will get it, but it's doubtful that most laypeople would.

So the tl;dr here is that they'd recognize most saints and pictures of Christ and his life from what they'd absorbed as part of the general culture. They'd probably recognize the high points of the Bible that would appear in sermons. But there's probably going to be some stuff that goes over the head of the layperson.

I only aim to answer one part here: brochures in the middle ages would be out of the question. That would involve an entire cycle of commodity production that the class structure of medieval Europe could just not support. For instance, in the early modern period in English churches there would be a copy of the Bible and of Fox's book of martyrs chained to I believe the pulpit, but perhaps elsewhere. The idea being that congregants could read from the scripture and just one other religiously/culturally important text. In other words the church, a typically financial secure institution, had only two books available to share with the community. And these copies would be printed, your question is about European culture a few centuries before the press. I know your question about brochures was probably joking, just thought I'd give an answer to that real quick.

Non-answer to the rest of your question. From what I can remember of encountering the question of church architecture a good starting point might be the cathedral at notre dame. Cliche, I know. But that building replaced a known earlier cathedral at a near by spot, was one of the first prime examples of 12th century Renaissance architecture, and it's in Paris so there is a wealth of good sources around it. If I remember right it took like 80-90 years to build, which would be plenty of time to build discourses over the meaning of statues, paintings, windows, and the like.