In regards to (1), sometimes using the phone is both a symptom and the cause (in a reinforcing cycle). In my case, I would use my phone in bed before falling asleep to avoid having to confront thoughts I would have while drifting off since I could stay distracted until I was seconds away from passing out. Unsurprisingly, I would have terrible quality sleep (and I suspect many of the psychological problems mentioned in the article stem from problems phone addiction causes with sleep).

Once I moved the phone to another room at night, I was forced to fall asleep without being distracted. Being alone with my thoughts was extremely uncomfortable the first few nights, but it got better. Now I'm used to falling asleep without distraction and am more in touch with how I feel. So my phone was causing me to become out of touch with my thoughts/feelings which would in turn make it even more uncomfortable to confront them, so I would turn to my phone for distraction and this reinforcing cycle continued until broken. The phone was both a symptom and cause of my sleeping problem, so removing the phone removed the cause and fixed my sleep.