Hi there,
I lived in Tanzania for 2 years, am back in the U.S. now. NGO full benefits can depend on the NGO. Some r better than others. If they are paying for education, transport, housing, medical, 1 or 2 flights home per years (for all family members) then it can be really good. Expect to spend what you are spending now, to maintain the same living standards.
Work for the spouse will depend on what they can do. The hardest thing is finding an organization willing to hire legitimately and going through the hassle of obtaining a work permit for potential employee. The work permit is a real p.i.t.a. for employers and getting caught without it can mean deportation. There are however, some entities who hire discreetly without the work permit. Those kinds of jobs are VERY hard to find as you can imagine.
The healthcare is limited although there are a few good maternal clinics there. The first is the IST clinic. Good service, international doctors, but pricey for the average Joe there. About $50/visit (I think they may have a maternity package for a fixed price) The other, more reasonable option is the Aga Khan Hospital. They have a maternity package for about USD 300 (all pre-natal visits and vaginal delivery) C-Sec is extra. Dr. Simbakalia is the best Obstetrician I have come across there. Tell her Patricia sent you. She takes care of many American ladies until about the 34 weeks then certifies them fit to fly.
Let me know if I can be of further assistance by emailing me or posting here.
Cheers,
Patricia