Qatar foundation is a good company and nothing to worry in joining the company. Make sure the living cost is very very high in Qatar, Perticularly house rent is very high. It is better to negotiate with the company that all facilities including accomodation should be provided by the Company

Regarding the School. Nothing to worry as Indian Schools are very good here and no problem for getting the addmission.
Make sure if company will bear all facilities including accomodation, Transportation, Medical facilities, and other basic requirements, then average Monthly expensis for living for a small family (2+2) is around QR 2500 to QR 3000) p/m