1. 这个句子里的“玩”怎么翻? Play, use, hold?
play&use will be fine,hold is not suitable.
2. 句子里的“因为自己玩手机“ 有什么意思? Because they themselves use smartphones?
Yes,correct.I'm not prefer "paly with",it sounds odd.
3. “觉得对不起家人和朋友们” = “feel bad/guilty toward their family and friends”?
Good!