Both areas are fine really! We live in between those two areas. Travelwise greenwood/kingsley is a bit better I reckon especially at peak traffic. As it gets busy starting at whitfords to reis highway.
Just use google maps with depart/arrive by times to see commute times.
Whitfords dog beach is super crowded, I don't like it. Quinns is very quite.
no idea about high schools, sorry!
Crime is everywhere, but those suburbs are pretty good.