I think the proper answer to your inquirer's question is: The Bible is NOT a history book. Anything in the Bible dealing with faith and morals is the word of God (except possibly those instances where He changes His mind from the OT to the NT). Anything dealing with history (creation, Bel and the Dragon, walls come-a tumblin' down, etc) were stories to instruct and entertain. This planet is some 10 - 15 billion yrs old, and dinos had lots of time to live and die. The creation account is poetry, not fact.
Appreciate your e-mail. You have packed a lot into a few sentences. To help sort out some of these difficult questions, a good place to begin is with what the Catechism says about correct interpretation of the Bible (nos. 105-114). As you sense the important thing is to determine the literary genre of any given text--e.g. historical writings, prophetic and poetic texts, etc. (cf. no. 110).
To apply this to the first chapter of Genesis, I would say you are correct to identify it as poetry. It is an intricate and beautiful balanced composition of six days of creation leading to the seventh day, the one dedicated specifically to the Lord. Because it is poetry does not mean it is "not fact." An example which comes to mind is the poem The Charge of the Light Brigade. The author was trying to bring out the inner meaning of an actual historical event. The poem might not include all the facts, but that is because Tennyson is concerned with something more than a video replay of the event. It is the same with Genesis. The author, inspired by the Holy Spirit, is trying to express for us the meaning of real events: creation of the universe, the creatures on the earth, man & woman. From there he explains how such a good creation got so messed up.
After the Fall we hear about the first fratricide, a primeval calamity and an early technological achievement. At that point we enter into events we can connect with our known historical accounts of the Ancient Near East. Determining the accuracy of any specific event described in the Bible would involve a painstaking process subject to constant re-evaluations. For instance, I notice that archeologists used to discount the story of the Joshua and the walls of Jericho, but now have found new evidence which has made them re-consider their earlier scepticism. So it goes.
What you state about the Bible's primary concern (faith and morals) is true enough. The Scriptures teach us the truths necessary for our salvation. As Augustine said, "The Bible shows us how to go to heaven, not how the heavens go." Where a single soul spends eternity is more important than all the scientific questions rolled into one. For that reason it is so important to remember what the Catechism calls the analogy of faith (no. 114). It means that we must interpret any given scriptural text in light of the whole Bible and the entire tradition of the Church. That principle is a matter of simple logic. If God is the ultimate author, he cannot contradict himself.
I hope this helps some, Tom. Please feel free to send any further question or comment. Perhaps someone else would like to jump into this discussion.
Fr. Phil Bloom
Biblical Interpretation and Homosexuality