I understand you want the best and the 4 bedroom villas in the compounds (where expats mostly live with security, pool, kids playgrounds etc) can stretch to 27000per month, but you should definitely see whether your employer can provide housing or at least arrange it for you. They have more bargaining power than individuals and i would only recommend gif you going it alone as a last resort because tenants have very little rights here in comparison to say the uk .

Can't advise on school costs other than to say the best places like Doha English speaking school have waiting lists so contact them now about place availability.

As for activities you could join a beach club for a place to go at the weekend, there are plenty of things for kids to do here if they like sport... Tennis, golf, sailing, wakeboarding, scuba etc