You had a bad book, then. Those aren’t beginner topics. Don’t learn to read music, it’s a waste of time. I will die on that hill. Use tabs and listen to the song to get the timing.
You don’t need to know many forms of chords at the beginning. Just memorize 4 of them and you can play most songs.
Barre chords are really hard. I don’t think I learned them until like my third year of playing guitar. You don’t need them as a beginner.
I used to teach guitar to beginners. Trying to run before you can walk just gets you frustrated and makes you want to stop trying. You need to learn the basics before you can learn advanced stuff. By basics, I mean, how to strum a single chord. So many books and teachers want to start teaching reading music or chord notation right away, and that’s just dumb imo. Just get a feel for it. Strum open if you have to until you feel comfortable strumming, then add your fretting hand into the mix to make a chord.