Before this week, I knew none of this. I started on the guitar chords a few days ago, but I wasn't getting very far, so I learned the bass part instead, and then the introductory electric piano phrase, after which I discovered that there really aren't many guitar chords. Mostly, the guitar doubles either the vocal melody or the bass part, which - until learning it - I'd never noticed.
I'm not sure if I have the parts immediately before the choruses correct. It seems like it's different every time.