It seems like you have a ton of data. I personally wouldn't be satisfied without most of his symptoms pointing to one main diagnosis. The slow walk, bent arm, and palilalia sure sound like primary symptoms that would fit together in some distinct way.
From my side I was fishing to understand if his distinct set of gifts and challenges fit mine or possibly my son's (but they don't so much.) For visualizing mechanical systems, I was thinking along the lines of being able to describe the connections in a motor or to know that if one cog rotates one way, then another rotates another way. Basically internal mechanical aptitude contrasted to what vision or dexterity might limit outwardly.
Numerical awareness seems to have a specific area of the brain associated with it. In addition to it's contribution to math, a basic guage of it is the ability to sight compare quantities and judge quantities without counting. As my son is slowly building out his visual associated skills; things he had problems with visually like judging quantities are coming up to speed. Since his impact was with eye coordination, his functionality was significantly better with his good eye than with his bad eye or both eyes together.
