Hanoi with children

I can answer some of your questions. Firstly, Vietnam is a developing country, so although there are some very good docotors and specialists, they are thin on the ground and most hospitals are not up to international standard. Other posters may be able to give you specific answers for Hanoi.

School starting age is seven in Vietnam. I doubt if you will be allowed to send your children to government schools, which teach a very narrow curriculum focused on the rote learning of things Vietnamese and maths. They do not teach children how to think.
So-called international schools are very expensive and the quality of teaching varies a lot. You need to get specific advice on individual schools  and their syllabuses.

I strongly advise you to come and visit Hanoi before committing yourself and your family to the inconvenience of moving.

Thank you Ralph. I am hoping that I might get a reduced rate for my own children if I work in the international school.
My daughter who has healthcare needs is usually very healthy. She just needs supplies like feeding tubes etc. I'm sure we could get these shipped over if it came to it.