Question about a sentence including the「す」with question mark at the end of a sentence


Here is the sentence I mentioned.

> ほう その良家のおじょうさまたちだけがなぜ 肉親もおらん少年院に入れるん **す？**  
>  そこのところをはっきりしてもらいたいもんだね

I have 3 questions relating to it.

  1. Is it a short colloquial form of 「ですか？」?

  2. Does the word 「なぜ」, in this sentence, mean 'why'? If not, what is the purpose of it in this case?

  3. Can I translate it as 'Hey, that is just a group of daughters from noble family which is the reason why they can get in to the reformed school, right? Please explain the reason to that point.' 




Yes, that …るんす？ is a slangy version of …るんです？ and the なぜ stands for "why", but
the whole sentence doesn't affirm what you described. Instead, it wonders or
suspects why that's that (or even doubts that).




Yes, that …るんす？ is a slangy version of …るんです？ and the なぜ stands for "why", but
the whole sentence doesn't affirm what you described. Instead, it wonders or
suspects why that's that (or even doubts that).

