The features have been provided on the basis of the variants and cost, if the school van variant doesn't feature hi-roof AC vents, you can get it fitted by customizing your vehicle. Again, the speed governor can also be installed as an accessory, it is not mandatory in all the states so Tata offers it as an accessory.
They are not offering any such discounts on Winger School Van, but it is possible that some Tata dealership is offering such discounts. You will need driving license, address and id proof to get the school van. As you are willing to use the vehicle for commercial purpose you will need to register it in commercial vehicle category, where you will need the require documents related to your business.