DS(4y2m) also gives a blank look when asked an easy question.
He has never been one to draw or colour because of perfectionist issues but a breakthrough came for us with the book 'Ish' and his space obsession (alien people, buildings etc are supposed to be odd shapes smile )
He loves taking things apart also.
I have no idea how a fit will happen at school as he is an introverted (but not shy) boy, reading gr 3 level, maths probably gr 1/2 level, general knowledge/science mid to late primary but socially closer to his age. We are thinking of an initial skip to gr 1 next year with hopefully subject extension, +/- another skip the following year. One step at a time... He would love homeschooling in some ways but at the same time some of school would be potentially good for him. It will be quite a journey for us all...