- How long do I need to practice per day, like 1 lesson or 2 per day, or for a specific amount of time, like 30 minutes a day?

You don't need to do anything. I think for most people who ended up being a music professional it started as a hobby they could not let go off. And they got better and better, with time. Just see where the day takes you. Personally, my absolute minimum a day is 30 minutes. Yesterday evening I have been playing from 7 at night until 9 at night. The day before from 7 until 10.

- I know it sounds kinda rushed and silly but after the course, will I be able the write a song all by myself? Let just say a new song being released, will I have the ability to find the right chords and notes, and know how to play it by myself?

I have been writing lyrics for over 15 years now. Don't do it as often anymore. But, the hard part of it is to let the inspiration flow, let it come to you. I am not far enough in my guitar journey to have a real say in how this translate to guitar but knowing to transition for C, D to G and E minor for example, would give you the capability to make a song. Will it be your master piece? For now. Then, you look back in 10 years to your first song and you smile.