Btrudy:
I'm not sure if you're going to see this if you're not on the forum anymore, but I'm going to try and figure this one out, if you do read it, feel free to correct me if I misunderstood you.
I'm guessing you're referring to how much of the bible should you elaborate on to the younger generation, possibly under the ages of 12, because let's be honest here, if the Bible was made into a movie, it would be rated for mature audiences. First off, don't ever go for another "version" because I haven't come across one yet that doesn't change the context of some vital doctrines. Second, don't ever treat children like they're stupid, and try not to make anything a mysterious taboo secret either, be direct, but also be age appropriate.
As for what to teach them? Well, teach in a language they can understand, a child can understand that a lie is bad, and Christ said no liar shall enter heaven. Revelation 21:8
But the fearful, and unbelieving, and the abominable, and murderers, and whoremongers, and sorcerers, and idolaters, and all liars, shall have their part in the lake which burneth with fire and brimstone: which is the second death.
Once they understand the weight of their actions, that's when you can lead them through doctrines of repentance and faith which...well, depends on the child, take it on a case by case basis. And as far as other sections of the bible go, show them what the bible is talking about in context and guide them through what we can learn from them, for example you wouldn't go into the nitty gritty details of the story of David and Bathsheeba to a 5 year old or the intricate details of how gruesome the crucifixion was or the things in Israel that Isaiah, Jeremiah and Ezekiel were rebuking in the nation, but better yet go through how the bible says the family structure should be, how God is near to those who are of a contrite spirit, how we should be charitable to others, all of these kinds of things.
This is a major job that is for us, to raise the next generation in Christ as much as we can, it's something I'm scared to death about messing up when I have children, but with our children, as with the lost...we should never compromise the truth for ease of understanding...if they don't understand it yet, then we should pray and ask that God will give them understanding, but something essential we need as teachers is patience.