1. Most assuredly it was not by God but rather by one who purportedly heard the word of God.
2. I don’t think its serious inquiry to engage on what was and was not “inserted”. Old Testament scholarship is an ongoing study with various lines of historical inquiry. It is the stuff of study that constitutes the basis of degree and postgraduate degree programs at leading colleges and universities. To put it simply, these are not answers that one can either provide or explain in a sentence without more queries to follow.
3. Here again, the deadly destruction of innocent life including children whether done deliberately, selectively, or with high probability of its consequence, or with reckless indifference for the bloodbath that follows, are all modes of killing with little substantive differentiation. To make distinctions is to make ourselves complicit in the horror establishing post hoc rationalizations in the process.
4. Yes, I saw the movie and the one in 1984. Liked all of the 1984 version, and some of the 2010 version. Admit to a bias here. Took Greek mythology and advanced math in college.
This was a surprising admission! This begs the next question: Was the command to slaughter, in 1 Samuel 15: 3, a command from God?
I'm looking forward to watching the movie, by the way.