There are lots of maths based toys (cuisinere rods, mosaic shapes etc). I think maybe you should work on him doing things other than writing though. Physical play is necessary for health and it is easy for a gifted child to only do the stuff they are good at. This can lead to risk avoidance and perfectionism. I would talk to the preschool about providing more support to help him try activities outside his comfort zone.
If he can speak engish himself without much accent he will probably work out the word in the accent he has. That is clumsy but if he hasn't picked up your accent through you learning to talk it seems unlikely he will read with one.
