Watch Apple 3

I would like to buy series 3 for my grand daughter as [mum and dad] want to keep an eye on her safety protection,

can we do that through cellular or gps.

As I understand the gps is circular meaning fitness which is only within x amount of local gps would this be correct?

What we would like is for her to answer calls and send and answer sms, most importantly we need gps location and sos calling. I've looked at other watches and in my opinion are way to young for her.

Also I understand that either way its got to be connected to an i phone and the watch doesn't have stand alone gps [trackable] would my assumption be correct.

Could someone please clarify these questions for me thank you.