What city? I'm in Lae and there are several families here and we have preschools. Port Moresby is much, much larger in terms of expatriates, families, and things to do.
As far as safety, it's what you make of it. You have to be smart, but I've yet to have a serious problem or have anything scare me away. Again, it also depends on the city and where you would be living within the city.
If you have specific questions, I'll be happy to help or at least try to give you names of people that can be of specific assistance.
Wendy
