I know that Santana's character (Naya Rivera) does. Not too sure about any other cast member though!
yes
No
Yup
Naya Rivera quit. I read somewhere that Mark Salling does. I saw a picture of Chord Overstreet smoking.
Yes, its the same Grace Summers
Yes
Yes, all the real cast.
The Glee cast lives in berkshire california. Near the set where the show is filmed.
the whole glee cast
18
Of course :D