You offer another interesting idea, that Catholics are defined more by their communion with the Church rather than with their doctrinal beliefs. This is similar to Judaism's definition of a Jew as the son of a Jewish mother rather than someone who believes a certain set of doctrines. Perhaps it is my own Bible-Belt upbringing, but I always thought that beliefs were pretty darn important and that a political unity in the place of doctrinal unity is a will-o'-the-wisp. However, I note that there are rightwing Catholics who insist that it is Catholicism that demands doctrinal correctness while Fundamentalist Protestantism is an emotional experience.
As to a lack of "fire and brimstone" preaching, I would advise that you should appeal to the culture you hope to reach (granted, no one really wants to reach Fundamentalist Protestants--white ones, at least--since they provide a convenient scapegoat to make all other religions look respectable to secularists). I might also suggest that Catholics don't want to hear about Hell because they can still go there. Calvinists can listen to sermons about Hell all day, since (in the words of Baptist preacher Charles Stanley) they "couldn't go there if they wanted to." But this raises an interesting question: isn't it the people who are in danger of going who should be hearing about it? And why do Calvinists have such an interest in the subject since they are "eternally secure" from ever going there?
Here we have somewhat of a paradox. The Church teaches that the Bible is inerrant in spiritual matters, but it may contain imperfect historical accounts and allegorical language. We also believe that it needs to be read with the intention and the mindset of the ancient human writer. How do we know which is which? From the Church. Our critics would say that to us it is the Church that is really inerrant, and they would have a point. We believe that God revealed himself in a number of ways, but most centrally and importantly he revealed himself through the person of Jesus Christ, who is called the Word. Thus to us the Holy Scripture is not a What but it is a Who. Now Christ gave us the Church directly ("I will build my Church") and the scripture through the Church (who is also not a What but a Who, His bride). The scripture is a very important part of the Revelation, but it is not the entire Revelation. The dogmata of the Church, -- consisting of the Holy Tradition and the teaching of the Magisterium of the bishops is another part of the Revelation. This can be endlessly debated as it contradicts the Protestant sola scriptura, but for our purposes here it is enough to simply state that this happens to be the Catholic belief.
Of course, scripture is discernible through reason to a great extent, but when in doubt it is the Church who interprets the scripture. In the Creation, we'd point out that some of the language in the Genesis is clearly metaphorical as it uses everyday words to describe cosmic events. It would therefore be without warrant to necessarily understand the six days as our conventional time measure, or to understand the making of man from mud in the literal sense of God shaping man as a clay sculpture and putting a soul in. You could interpret it that way, but you don't have to. The Church is simply silent on the chronological duration of the process of creation, or on physical mechanisms of the creation of life. You can hold the fundamentalist literal creationist view and be perfectly Catholic, or you can hold the view that the world was formed like the astrophysics teach, and be perfectly Catholic.
So, what parts of the biblical account of the Creation are dogmatic teaching? Off the top of my head:
This is about it.
there are rightwing Catholics who insist that it is Catholicism that demands doctrinal correctness
You don't have to be right wing: Catholicism does demand doctrinal obedience. A Catholic is supposed to strive to learn the doctrine, obey it, and work to embrace it. For example a Catholic is supposed to learn that contraception is a sin, and not use it, even in his heart he does not understand why. Next, he is supposed to seek better understanding till his obedience becomes a joyful choice. Sacramental life of the Church: confession and the Eucharist, as well as prayer and acts of penance, are to help the Catholic in this struggle.
Nevertheless, a wayward Catholic is still Catholic. This is for two reasons. First, anyone validly baptized is Catholic, including the Protestants and the Orthodox. Those who continue in obedience to the teachings of the Church remain Catholic even if they would not call themselves that. For example, the Orthodox, even if vehemently anti-Rome, are theologically speaking Catholic if they obey their Orthodox bishops. Given a greater culture of church life in some Orthodox lands, it is quite possible that there are more Catholics in Serbia than in France.
Second, we believe in progressive justification and reject the salvation theology that considers some men once and for all saved and the rest once and for all reprobate. When a Catholic fails short of some precept, but struggles to improve, he remains Catholic, and a rather typical Catholic at that. It takes first familiarity with, and then a defiance of, the Church teaching to make one non-Catholic. Even that can be restored with sacramental repentance.
isn't it the people who are in danger of going [to Hell] who should be hearing about it?
Absolutely. I am not approving of the lack of serious preaching on the spiritual dangers, and in fact am a great admirer of fiery preaching style of fundamentalist Protestants so long as they call to repentance and steer clear of Calvinistic presumtions of election and reprobation. I was merely pointing out to the Catholic eccleseology of salvation that, unfortunately for the liberal West, at times leads to kumbaya homilies. Not all Catholic preachers are like that. In my church I hear the direct and strict instruction on Catholic way of life from Monsignior Kavanagh, who is famous for showing former CA governor Davis the door. On EWTN we hear the inimitable Fr Corapi. We are doing better than a casual observer might think.