1) Language input options: No idea about this as i read books in English only
2) Durability : I bought it in Dec 2012 and it is working fine till now. I kept it in my home only for the first 4 months and then started carrying it in my backpack. It was during this time that few members at this forum started reporting that the screen is delicate and it could break when carrying in backpack etc. I was afraid so i made a foam/sponge case and i insert my onyx in that case when carrying.
3) File structure : Yes
It works exactly like that of windows explorer.
I hate itunes-esque file structure myself and nearly all my devices (sansa, onyx, mobile, laptop) have directory structure