re: Brother wants me to teach him how to play guitar. Where should I start?

Most people are never going to become good guitar players. I know I didn't. So, he needs to do as much as he can the first 6 months - I would teach the basic open chords, strumming patterns, but get right to songs quickly.

Sounds like mostly acoustic, so I would skip power chords (those are stupid easy to go back to later) - and focus on some slower songs, then a few faster ones - maybe harmonics if called for.

Good basic acoustic guitar picking and even fingerpicking would be my focus.

Just my $.02 (Caveat: I'm more of a guitar collector than player, although I insist I'm going to start playing again regularly - )