My whole family has curly blond hair.
"Blond and curly hair" is very unnatural in English, but it is the literal translation of the French, I suppose.
"Blond, curly hair" should count. In English "blond and curly" sounds awkward.
all my family has blond curly hair should be accepted. You wouldn't say blond and curly in the UK, just blond curly or more realistically curly blond
all my family have blond curly hair, marked wrong.
Yes. Using typical adjectival order from English, "curly" would most often precede "blonde."