Can anyone tell me how long it takes for a Dominican citizen (adults and children) to get a passport, what documents are needed and how much does it cost?
It can be done in a day. Cost is a couple of thousand pesos.
Never, ever pay for it. If they want a passport, let them buy it. If they can't afford it, then they will never, ever get a visa, so why bother in the first place.
You will need their birth certificate, cedula and passport photos and it helps to know someone at the passport office...ask around I'm sure someone knows someone.