Before starting GT7, start with
My First Gran Turismo. It's the demo version of GT7 found in the online PlayStation store (in your console). Best way to find the demo is to type in the full name in the PS Store's Search tab. By completing all events in the demo, you'll be awarded with 18 cars that you can access the next time you log on to GT7.
After that, you can follow along with the Menu books, as some of them ask you to do certain things, such as "obtain the National B License." I think the highest license you need for the Menu Books at the end is Normal National A.
A lot of the menu books award you with cars as you complete their events.
4. Do I need to tune cars to be able to win races? How do I know how yo get the best set up?
Depends on the event. Some will require you to tune your cars to meet Performance Point requirements, but there are some events where you might be able to get away with using a bone-stock car. The GT7 Car Tuning subforum here will be handy for finding the tunes you need for specific races or cars.
As for learning with the controller,
My First Gran Turismo might be able to help you get familiarized with the controls. Same goes with the license tests in GT7.
Edit:
There are some events in World Circuits that go by the following Performance Point (PP) terms:
No PP Limit - As long as the car fulfills the car restrictions (if any, such as the car needing to be from a certain country), you can enter with a fast car for an easy win.
Suggested PP - While the game suggests to tune your car around a certain PP range, you can still upgrade you car beyond that suggested number... As long as you car meets any other restrictions, if any.
PP Limit: ### - Your car must be at this Performance Point limit or under.