About the soothsayer, not sure if this helps you or not but I believe that he is shown to be a fake and a swindler. It didn’t seem to be promoting this at all but rather showing it to be foolish.
These things are all very indicative of Rome and the culture at the time. When you came to this part, you could possibly read in the Bible how the early christians handled these types of situations. There are several occurances throughout the New Testament of people such as soothsayers and such that the disciples and Paul came across. This may give your kids somethings deeper to chew on than what they would get from the story alone and bring Christ into the situation.
blessings,
Miranda