Który is asking 'which one of the finite set of choices is the one' while Jaki is more like "what kind of":
"Którego psa brakuje?" – Is asking which dog is missing; most logical context would be, I don't know, like aftermath of a flood in the kennel and the expected answer would be "Azora"(a dog name).
"Jakiego psa brakuje?" – Is asking what kind of dog is missing; most logical context would be if you are preparing for a dog show and you have a list of dog breeds you want on that show, so you ask which breed is still missing; expected answer would be something like "Sznaucera"(A dog breed).
Obviously, there is certain overlap between the two, but generally they ask about somehow different things.
It doesn't. If you really need to make it plural, you need to count them and use a collective numeral: for example "two doors" (is this even correct?) is "dwoje drzwi".
If you can't give a specific number but still need to stress the plural... well, that would be really problematic even for a Polish person :|
Sometimes people say something like "dwie pary drzwi" (two pairs of doors?), but this is grammatically dubious, because frankly... does it mean two doors or four doors? It's rather meant as two, but as "para" already means two...
i put "what type of door are you looking for" and got it wrong, and i disagree, English is my native language and 'type' and 'sort' are interchangable, and one correct version of the answer is 'what sort of door are you looking for'. Don't see why my answer can't be a 3rd correct option.
"Which door are you looking for" is something you would ask Sully and Mike at the end of Monsters. Inc. You would answer it by "I am looking for my bathroom door". "What kind of door are you looking for" is something a door salesman would ask you. You would answer with "A wooden door" or "A bomb-proof door".
Am I right in thinking ich means they, and the ending of szukacie- cie, means you? So to me it kind of seems like the the question asked what kind of door are they looking for, but at the same time, what kind of door are you looking for? So I would of thought so say what kind of door are you looking for would be something like Jakcie drzwi szukacie? Or Jacie, or even just Jaka or something that puts cie on the end of Jaka. From the answer being Jakich I can tell this is correct, but can someone please explain to me why Jaka has ich on the end and not cie (this may be a dumb question but I've only been learning Polish a few months so I'm good great yet) thanks