There are 3 different school districts in 11550. Rockville Centre, Uniondale and Hempstead. Rockville Center is one of the top rated schools on Long Island. There is a part of south Hempstead that is zoned for Rockville Centre schools. i live there and my kids flourished in the schools. If you are looking to buy South Hempstead is a great place to raise a family.
I grew up in 11550 and I can tell you that the school system in 11550 has deteriorated to be the worst on long island. it is a mix of black and latinos. some areas are nicer than others, you would have to go there to get a feel for what you like. it is a transportation hub, so it is the best place to live if you are going to travel mainly by bus or LIRR. There is shopping.