mlsoft, you note requires splitting the response into few posts. I'll start with the one which I see as obvious, the issue of Job. I presume you know that the final assemblers of the old testament had a great problem with the inclusion of the book as part of the old testament. The reason was that without the last chapter, the book could have been interpreted as heresy and only the reconciliation (and some researchers claim the last chapter was written at a later date to allow the book to be included) made the whole book "acceptable". That book raises the deepest theological questions about the almighty, his powers, the limits of his power etc. It is the only book where "Satan" is a major "player" (well a possibly later book Zecharia also have some "dealings with Satan), the word appears in the Torah only in the story of Bilham, but not as what we know as "satan" but as a barrier to overcome. The concept of Satan (derived from the Hebrew word "Sitna" meaning pure unadulterated hate) is quite late in Judaism, as is Job. In essence, it is a "Din Torah" of a kind, in which the response to doubts that Job experiences, is given as his ignorance of the creation (was Job the first evolutionist and the almighty was giving him the first lesson in "creationism"?). The analogy of choosing Job for Satan's machinations and Israel for the almighty trials and tribulations is, however quite correct, except, of course that Israel, unlike Job, is not sin less. Of course, the presence of Job in the old testament, the one declared to be absolutely righteous (without sin) by the almighty himself, throw a monkey wrench in the dogma that we are all born sinners..., Job wa not and Noach was not.
As for kids, some are innocent some are not, I know I had to teach my youngest that some times he must "defend his turf" or he'll be stepped all over (he took the "thou shall love your friend as you love yourself" literally early in his childhood. I think that most of all children are curious, not bad or good, and in the growing process they discover the limits of their domain, the differentiation between "good" and "bad" is a slow lengthy process, but as I taught them, if you don't know if what you do is good or bad, imagine and put yourself on the receiving side of your own actions, and then decide if what you are about to do is "good or "bad". It worked most of the times (to be truthful, only three out of four <g>).
As for Numbers 14:18, gosh who translated that? Here is my translation: The Lord is patient and righteous, and bearers of sins and crimes he will not forgive (the hebrew here is "Nakeh lo yenakeh", meaning clean he shall shall not clean or in my translation unforgiving), he counts (really recounts) the sins of fathers on their sons and on their third and fourth (generation, sons being second generation). If you are going to read the bible literally, you'd better start learning Hebrew since existing translations are short of the original (the Douay translation is quite far from the one you cited as well).
Zeev