Hello maxie. Sorry to hear about you're disability, I know what it's like, my father is paraplegic and has hand controls in his car.
The power steering turns itself off at a certain speed, to make driving more enjoyable I think, but it becomes light when at low speeds for easy manouvres etc. Not sure if it can be permanently switched on, someone will be able to help you though here on the forums.
As for the scratches n the paintwork, they are swirl marks, the only way to properly remove these is with a machine polisher and with the right valeting techniques and products. A valeter will be able to give you're car a good going over to remove every imperfection in the paintwork. Prices vary, ask in the detailing section for more imformation.