[rsync]

"I'm not sure how I'll navigate it."

I am not going to address the broad set of questions here but I want to point out that two items exist:

1) No-data SIM cards ... they call and text only ...

2) imessage only access point - fairly trivial to set up.

So ... a child can be given a phone - even a smartphone - and it can't be used as a social media device when the family wifi turns off. Further, you can heavily restrict family wifi without curtailing normal phone talking if you have an imessage/facetime only access point.

Again, no magic bullets here but some tools that you might find useful.