Would it be better to learn on expert difficulty as that's how you would learn real guitar, not just 20 notes from the song.
Agreed. I think it might be rewarding first to try to learn a few of the easiest songs on expert, and learn them properly so that you can play them without too much struggle before moving on more challenging songs. If you're a beginner don't jump right away to play those more difficult songs, you'll just get frustrated.
HMX, can I pls have the Cinderella "Don't Know What You Got" pro upgrade which I bought 8 months ago?