they are transparent because if they were not they would not let you see outside and they would not let any light inside.
transparent windows you can see through them and translucent you cant see through them
Yes, though sometimes they change the color of light, or more accurately they allow a certain color to pass through and block other colors.
yes, at least all the ones you can see through.
It depends of how foggy. If you can still sorta make out shapes through it, it's translucent. If absolutely nothing is discernible, it's opaque.