Genesis

I tend to consider myself a pretty religious/spiritual person (I am Catholic) so I enjoyed reading this. I had been taught the stories from Genesis when I was younger at CCD classes, but fortunately I can now form an opinion on them and ask questions.
Heres my question. On page 8 God tells the human not to eat from the tree or he will be doomed to die. Does this mean that had Adam and Eve not listened to the Serpent and lost their innocence would humans be immortal? Their eating from the tree caused them and all humankind after to lose their innocence, to feel embarrassment (realized they're naked) to fear things and also to be sinful...causing God to recreate His people with the Flood... so that is just a thought.
Also, what equaled a day? Did God create the sun and the stars and the moon in 24 hours? or were His days equal to 10million years, thus raising questions of evolution? Adam was created as a full grown man, or at least that is how he is always portrayed. But did he have a childhood, did he grow up to an adult under the eyes of God? Since God did not want Adam or Eve to eat from the tree and lose their innocence, is it possible that childhood was only created after this infraction? Childhood is considered as a time for people to learn about social mores and to experience situations that will help make better functioning adults, but perhaps it wasn't in God's initial plan for humans, maybe we were supposed to begin life as a physical adult and live in blissful innocence.