How much gluten should I add to maida flour for bread, and how?
You can, but you'll likely get better results if you mix it together with the flour before you put it into the machine. As soon as gluten is exposed to moisture it will start to uncoil, mixing ahead of time will make sure it's evenly distributed when that happens.

As for how much to add I am not sure, it depends on the product and how much protein is in the flour already. I'd start with a teaspoon and add more if it is needed in future recipes.