I don't quite understand the first question. "Didn't have" is the simple past of "don't have", the negative of "have", in those varieties of English that use do-support with "have" - most varieties today. In British English you will also hear "hadn't got" and occasionally just "hadn't".
You can use "worked" or "were working", but they don't mean quite the same thing. They don't express a difference in the objective facts, just in how the speaker is choosing to regard them. If you say "they were working", it either emphasises the continuing behaviour, spread over weeks or months, or else is setting this habitual activity as a background in the narrative that follows.