Great questions. Part of what the practice plans are designed to do is to reveal opportunities. It looks like that’s just what it’s done.1. In the key of G the chord progression is G – D – Em – C (no Am). 2. Both versions of C are good. The version I use here is more common in modern pop music.3. In the key of D the 5 chord is A. I actually teach students to count on their fingers… D, E, F, G A. I think you’re overshooting by one. That should solve that problem.But now for the opportunity…All of these questions are dealt with in the Beginner’s Journey, the last few Adventures. More importantly, you’ll get a chance to practice and use some of these things… including this form of C (also called Cadd9). If you’re interested in how this works you may want to do these lessons:Real Guitar U > Practice Library > Guitar TheoryYou’ll find these 5 lessons start simple but you’ll end up having a great foundation to build on. And more information so you can has more great questions.