Although corn, like wheat, rye and barley, does have a protein content it does not have the harmful effects to someone with celiac disease as the gluten that is in wheat. Therefore it is considered safe for celiacs to eat
I suspect not...cornflour is the same as 'cornstarch' as it is called in the US......there used to be a gluten-free flour available in Sainsbury's. But I do not know if they still stock it. You could try a health-food shop.
Cornflour/cornstarch does not contain gluten, with the exception of a 'wheat, (or wheaten)', cornflour which is rarely found, and where the words 'wheat', or 'wheaten', will be clearly stated on the packet.