Have you been to Cabrera? I suggest you come down and check it out. Note that your son's option for school would be about 45 minutes away in Sosua, or homeschooling, or attending the public school.
The area is lovely, full of lots of upscale villas and more wealth about to pour in. Lots will be happening in the area in the next two years as big players have bought in. But in the meantime, it is slow and quiet. You will have to provide your own entertainment in Cabrera. But 45 minutes away in Cabarete is a teenager's dream town with skateboarding, kiteboarding, windsurfing, surfing...
I do not know anyone in Cabrera who carries a gun, but of course there are persons that do so. It is true that crime is on the up in the DR, and you should be alert. For sure the owners of the house have already taken safety precautions in this direction.
You are talking more of a hamlet or small town, Cabrera is not a city. A woman can definitely walk by herself in all of Cabrera. Don't recall it having any dangerous slum areas.
Water is not drinkable off the tap in any city in the DR -- unless it is treated as some gated communities and resorts do. Others install filter systems. Take note most Dominicans brush and bathe with tap water, so one does get accustomed to it.
The North Coast is on a earthquake belt. But I think the death toll was less than 10 nationwide during the last earthquake some years ago.
Paradise will always be where you make it and where you may surround yourself with the people that you love. But Cabrera and Playa Grande area are a lovely area, naturewise. If the pay were good, the challenges of sourcing food materials not a bugger (meaning you will have to be creative and adapt), and you could arrange for transportation for your son so he is not bored, then definitely go for it. It could be the best time of your life.