Best wishes on your research.

I tried the lyric writing techniques: poetic rhymes, romance love songs, political "down with the machine" and what comes back to me is; instrumentals.

I find although I enjoy writing singable melodies, I just never found the niche to match the mood of the song with an equal lyric. So, rather than causing greater suffering in the world than there already is by my horrible lyrics and yet even worse singing voice; I took to the guitar. Now, with software like BIAB I am able to create melodies for other instruments as well. As a result, I look at it as BIAB brought a wonderful contribution to society; disabling me of the need to sing and thus write lyrics!

All that said, the method I have finally resolved upon for creating is: start with a standard chord progression and rhythm pattern against it. I play that several times to allow my mind to absorb the relationship taking place between the two.
Next, as I am listening I look for where I can tweak the existing chord progression or rhythms to enhance what I already like about the song. After this, I have now made a new friend.
I then travel with this friend for a little while listening for what I want my melody to say and with which voicing I am going to use?
Once, I have that in my head, I begin the recording process.
Then, like finishing a piece of wood I sand, and sand, add a little stain, and sand some more. Once it begins to shine I stop.
#5 - I cut my teeth on playing over my influence's material. That will always be my default because what drew me to the song is what also causes the creativity in me to write my own. So, they work hand in hand for me.
#6 - Depends on the mood I am in. My mind always is spinning its mix. And there are times when an original tune will stand out and other times when a classic tune jumps out at me.
#7 - over 40 years.
#8 - Yes. On and off for over 30 years. The best student age group I find is the one where they do not want to do anything else. Huh? Well, I have found remnants of that in almost every age group. Conversely, I also find the opposite in every age group. Hence, that is the reason I do not look at age as much as how they pass my initial quiz.
#9 - No biological relatives were musical. However, an in-law mentored me heavily in music being he himself was a recording artist that had several charted hits.
#10 - Much easier. They always show up on time.
#11 - same as #10
#12 - My biggest offense is "Rock Band". There is nothing more technologically more damaging than convincing someone they can play an instrument using Rock Band.

Cheers!
RickeG