There were different styles ranging from back, to side to front buttoning suits. The buttons usually ran to the waist. The two piece suits were mostly front buttoning. Matrials for rompers varried. The dressy formal suits were often velvet.
Few images exist of boys with long curls wearing rompers.
Especially around the turn of the century, Dutch boy cuts were popular with romers. I have little information about the conventions for wearing rompers. I believe that they were initially play wear, worn in the nursery or for play around the home. Dressy styles eventually develoed so they could be worn at even formal occasions. I am not sure at what ages boys wore rompers.