I totally understand, in that our district requires a certain achievement score in order to be considered for a certain math program. But, typically, many things need to be taught to attain such a score - the chicken-vs-egg.
If possible, in your case, I would give math instruction at home, on a regular basis, and with a specific math program, i.e., I would be very deliberate about it rather than random. You'd want to be sure that the math concepts are understood sufficiently for a strong foundation. That way, regardless of what is being taught at school, your child can learn and be challenged at his own level and pace.
On the one hand, memorizing is not cheating at all - indeed, many traditional school math programs involve rote memorization. On the other hand, I don't believe it's the best way to learn for many kids, especially non-traditional learners, and I'd worry that in the long run, practice may be better than memorization - it depends on the particular child.
As to your last question, yes, I absolutely have a child who, given a choice between A and B, chooses C every. single. time.
