The sounds are quite the same. In "cui" emphasise "u" or pronounce it as a long "u", instead for "qui" you have to put an accent on the "i". "Cùi/ cuui" and "Quì". :)
I put 'district' because noone in England talks about provinces bu this was marked wrong
Cui sounds just like qui? Is there any difference?
Yes. "Cui" means which and "qui" means here. (or maybe you mean about pronunciation only
and than I don't have a clue.)
I would assume they are pronounced the same.
How do we know that "he" is the right choice (instead of she)?
both should be accepted by the system, if you mean in actual conversation it would either be obvious from context or you could ask the speaker "lui o lei vive?"
Why can it not be "in which you live"? Doesn't the 3rd person of the verb include he/she/it/formal you? Thanks.
In formal you usually need the Lei
isn't vive the polite form of you?
Yes, but it's also the he and she form, "lui" and "lei" respectively. It's the same with the "loro" conjugation, which can mean "them" or the formal "you all."
Nobody in UK talks about provinces except Londoners sneering at non-Londoners ;p. Could 'area' or 'district' be acceptable?
These last two questions were already answered...?
Why can't it be 'in which you live' ?
in which or wherein?
Both are correct but perhaps 'hyper-correct' - they would seem over formal in ordinary conversation. People would be more likely to say 'where he lives'
How do you know when to use cui and when to use quale?