Sounds like you are doing fine.  Maybe even a little ahead.  If you can play along with songs you want to play, that's great.  Being able to play music on the guitar is the purpose of taking lessons, learning & practicing. 

Some of the topics you are asking about (changing keys, different scales & patterns) are well beyond beginner material.  And Fundamentals 1 is beginner material. If you keep working through GT material, you will eventually learn all that material & get it explained completely & properly.

Jumping from site to site might be slowing your progress with Anders, or causing frustration since they don't explain things completely.  But it is also a source of motivation to learn new things.  So, how much to focus on GT or jump around is a personal call for you.

But as long as you are learning, making progress & playing guitar, then you are doing fine.  Keep practicing!