not really. kids need communication, as well as adults: since humans are such social animals. what harms young people more is stuff that decreases attention span, unrealistic body expectations, etc not "communication"
anything that isnt very hard to run should be fine. ive personally ran a distro on an early 2012/2013 mac and it worked just fine. forgot what one but i know it was a very common mainstream one. i also somehow got kali on it so that was interesting too. if you want something easy and simple you should probably use mint or debian if they support imacs, otherwise? its really down to personal pref
not really. kids need communication, as well as adults: since humans are such social animals. what harms young people more is stuff that decreases attention span, unrealistic body expectations, etc not "communication"