how do I know when to use ci or ktera?
čí - whose
která - which
They are completely different words.
Is it a kind of correct sentence "Which woman is Žofie?". They normally say it like "What is she like?" or "Whose ... is she". "Which" is used with things, not people.
Nope, "which" is used with people as well. You must consider the meaning of all these pronouns. They are not the same.