If I just passed Q-school and I don't play in any tournaments for the whole year can I still win the ROY in the second year?
Not sure about that one man. I would recommend just playing the tournaments, especially if you're good enough where you can shoot around 13 under par consistently. It'll help build your character up, because you get more skill tokens when you're playing in the tournaments.
I believe the AI adjusts itself to your skill level, so the lower you shoot, the lower the computer scores will be. I think the lowest I've ever seen the computer shoot was a 52, but that was in one of the Majors, and I had shot under 45 in the first 2 rounds. So it takes a lot to get the computer to shoot low scores like that.
Best of luck man, and I hope to see that golfer of yours online sometime soon.