Yes, that's what it means, but your sentence is translated as "o que ela faz?"
In English there is a difference. A profession requires academic training and, more often than not, continuing education (you must take professional courses on an ongoing basis to stay current in your field). People often think of professions as white collar jobs and occupations as blue color jobs, although occupation can be any job. Does Portuguese not have that distinction?
What is the uses of "Occupation" in English? I've only read it in History books, so assumed it meant to take over, when a place is over-run, Never in a non-history talk.
Seu/sua is vague in Portuguese. It can mean his/hers, but more often it means your (voce)'. So Portuguese speakers generally use dele/dela so the listener knows who the speaker is talking about. It is easier to understand when these words are used in context.
It depends. We need context to know who "seu" is referring to. If it is clear that "seu" is referring to "her" and not "you", then you can use "seu". Otherwise, it is better to use "dela".