What engine or suspension modifications do I need to do for a drivers' school?
None! In fact, if you leave your engine and suspension in stock form, not only will it be easier on your car (higher-performance parts put higher stresses on your car), but you will also become a much better driver in the long run, because you will learn to overcome your car's limitations rather than relying on technology to do it for you. Improving the car (instead of the driver) short-circuits the learning process, and you'll get far less out of your school.
Modern cars are extremely capable, and there are very few drivers who can get 100% of that capability out of a stock car, much less one that has been heavily modified. You'll get more for your money if you put the dollars you would have spent on car improvements into driver improvements instead.