That कौन is almost identical to my Spanish quién. Indoeuropean roots saved me this time.
We’re told Hindi is an SOV language, but isn’t this OSV? Is there a reason the object is first? For emphasis?
Interrogative pronouns and adverbs generally follow the subject in second position, or later. Source: "Outline of Hindi Grammar With Exercises" (R.S. Mc Gregor). Does that make "चाय" the subject?
In Hindi there is no frozen rule as to the order, because you can easily understand what's the subject, what's the object and what's the verb. The rule is SOV but that can change if you want to emphasise something. Here कौन is the subject, if it was चाय the verb would have been पीती (चाय is feminine) and the sentence wouldn't have had sence.
Not in English at least. Unless you rewrite the sentence as "tea is drank by whom?"
Yes, to emphasize on the tea more than on the who - it would then sound accusative. Ps : I'm not a native, I might be wrong, but this is how I hear it