Hi

I love the ambition. I don't have much time but in short:

I practice an hour each morning. I forget exactly what Lisa teaches, but her courses are well worth the effort.

Songs are chords that sound good together, and luckily we have convenient tools such as "Chords in the key of"... If not here on the web.

Writing a song isn't hard, writing a hit is hard. At some point you will want to learn some theory, but I would finish Fundamentals first.

In terms of playing a song you hear, unless you have someone who has broken down the chords and strum patterns, that's tough to do by yourself. But it can be learned, the instructors here do it everyday.

In the meantime there are tools available. You might find your song here, or Ultimate Guitar or even on YouTube. Marty Schwartz (YouTube) is breaking down the latest AC DC album as we speak.

Very best of luck with your studies.