On the first one, I have to disagree with the author, he states that the primary pathways for growth are:
Mechanical tension
Metabolic stress
Muscle damage
I completely disagree, muscle growth is a neurological response to overload. Many years ago, it was thought to be things like muscle damage, but no longer. Even the American College of Sports Medicine recently changed their stance on this (about 10 years ago).
After reading the study in the 2nd link, I see how they are linking the neurological overload to the three things listed above, however I also think they are being somewhat misleading about the certainty of their causes and effects.