"At which stop do we get off?"
车站 is a standard word for both "train station" and "bus stop", though you can be more specific for each case. There are also other kinds of station and indeed 站 is used for things in Chinese that we use other words for in English such as busstops and taxi stands/ranks.
It is incorrect. For the location an action occurs, put it in front of the verb; for the location complementing an action, put it after the verb.
下车 is a compound word that comprises a verb (下) and an object (车) and it does not carry a location complement.
Please compare the following sentences:
Lit. At school I sit inside the classroom.
Lit. At the classroom I sit in the first row.
Usually the location, time, and person you're with will all come before the action, 下车 ☺
The English sentence makes no mention of a station. Whether the "stop" is a train station or a bus stop is unknown. Do Chinese people use 站 to refer to all bus stops?
站 refers to both a train station or a bus stop. Report it if they don't accept "station".
Isnt the subject flexible in this case? Wouldnt it be acceptable to put 我们 after 站 so long as its before the verb 下车?
Yes and no. Grammatically there's certainly no problem. Nonetheless I do feel it's not so natural, in the sense
of "At which stop do we (need to) get off?". I would not omit 要 in this word order.
在哪个站我们 要 下车？
I think it is just an issue of a different context due to the change of emphasis.