This makes sense to accept this translation, however in the long run, it may be easier to learn that hän is just a third person pronoun and can be translated to he/she. Literally, "who are they?" would become "Keitä he ovat?" in Finnish due to the plural affecting the question word and mean a group of people as we do not require this kind of version.
I'm just wondering... that would "a teacher and their students" actually translate to "opettaja ja tämän oppilaat" rather than "opettaja ja hänen oppilaansa" [a teacher and his/her students] - even though in this (incomplete sentence) we only see one singular subject at this point.
'Tämä' is literally 'this' or 'this one' and is used like the singular 'they' especially in cases where there are multiple subjects (that could be referred to as 'hän') and we want to specify that we're talking about the first 'hän'. But sometimes it's also used when talking about someone in a less personal way, so to speak.
In the case of "who are they" (singular) it would become "kuka tämä on" [lit. who is this], but we don't usually say that (unless maybe when pointing out someone from a picture etc.) And to be even more impersonal, one could say "kuka tuo on" [lit. who is that], but it can have a bit of a blunt and rude tone to it (even degrading, depending on how they say it) so I wouldn't recommend that.
Ja mitä kieltä hän mahtaa puhua? :)
Suomea, ruotsia, hindiä, viroa, espanjaa, italiaa, ranskaa, saksaa, hollantia, arabiaa, tanskaa, mandariinikiinaa, unkaria, japania, liettuaa...
(The -a/ä suffix there is the partitive, the nominative is just "suomi", "ruotsi", "hindi" etc.)
That's a very good point - I've also heard that Japanese '彼' (かれ, kare) used to be a gender-netural pronoun, but because of the influences from other European languages, they now use '彼' for 'he' and '彼女' (kanojo) for 'she' - about which I'm kind of disappointed.
The sense development seems to have proceeded from "that thing over there" to "that person over there [of indeterminate gender]". The specifically male sense of "he" only arose later during the late Edo period and early Meiji period, influenced by translations of texts from European languages
The usual word order is the one you said "question word + S + V", the others are rather theoretical and they sound strange in the normal usage.
You can form a question like this: take the affermative sentence, replace one of the words with a question word, and move it in the beginning of the sentence. For example "Hän on Anna" can be transformed into these questions:
-- Kuka hän on? = Who is she? -- Onko hän Anna? = Is she Anna? -- Kuka on Anna? = Who is Anna?
In Finnish, the verb changes with each person. In the case of the verb "olla" ("to be") the singular verb forms are "minä olen", "sinä olet", "hän on". For this particular verb all three are different also in English: "I am", "you are", "(s)he is". So if you are asked to fill in the personal pronoun in the sentence "Kuka ___ on?", the only possibility is "hän" because it matches the verb "on" already present in the sentence.
In Finnish all the verbs have different forms for different persons, not just the a couple of verbs like "to be" in English: minä syön, sinä syöt, hän syö; minä menen, sinä menet, hän menee; minä asun, sinä asut, hän asuu; and so on.