1. It would be clearer from the context of the full article, but it seems that the younger people and the phone-watchers are different groups. Maybe they overlap to some degree.
2. It's not exactly the structure you described. The pattern is this: "Subject+ Verb, as Auxiliary Verb + Subject"
This little inversion allows us to join the two phrases to say both phrases have the same situation. If we split the sentence into two sentences, they'll look like this: "...the younger people in his study were more likely to experience the phenomenon. The ones who constantly looked at their phones as a way of regulating their emotions were (more likely), too."
Some more examples:
"He began to run, as did the other competitors." (Compare: "He began to run. The other competitors began to run as well.")
"She'll come early, as will her friends." (Compare: "She'll come early. Her friends will come early, too.")
3. "Regulate their emotions" means to keep their emotions under control, and probably not become angry or upset.