I spent 8 years in TZ, and during that time our daughter ranged in age from 8 weeks to 2.5 years.
On the health side you can live safely. If you are flying you will undoubtedly be exposed to malaria, so you will want to be continuously taking antimalarials. Ignore those who spout about side effects of antimalarial drugs: a very common side effect of malaria is death. Obviously you take the usual health precautions you would in any developing country: filter/boil drinking water, obsessively wash hands, soak fresh fruits and veggies in weak bleach or permag solutions, that kind of thing.
Crime unfortunately is on the up in Dar, though it ain’t nearly as bad as in NBO. You’ll need a security service on the house, etc. If I had to budget for monthly housing and related costs, modest place, for a family in Dar I’d budget 2-3K a month, maybe 1500-2500 a month in Arusha. To include utilities, water deliver, guard services, etc. Don’t forget your health insurance, and of course you will want the policy with the medevac option.
You will likely want to have your kid/s in international school, for which basic costs are $12-20K a year.
The aviation community is small and fairly tight, tends to be younger, and a mix of expats and Tanzanians. As in all countries there is significant pressure to employ citizens, so you have to have sponsor for a work permit. Then of course you have to do the TZ conversion of your JAA or FAA license. Facilities are modest to what you are compared to, expect to spend time at NBB doing maintenance.
Personally I think it is doubtful that you would find an employer who would give you a package that would let you have a lifestyle equivalent to what you had elsewhere—it’s impressively expensive in Africa, which is why most the pilots tend to be younger, unmarried or newly married, happy to live rough and ready. And they don’t have the financial requirement of school.
But if you can work it out….some really exciting flying.