Unanswered Questions

So maybe I missed it but what was behind the door to the office that the mayor wanted into and where is the grandfather that the madman saved?

You get to see behind the door in the bonus game of the CE.

At the start of the game, the grandfather had died and sent you a letter, which is why you, the protag, went to the theater.

Yes, it is confusing when some action is not completed unless one purchases the collector's version, like the "mayor" going through the door. Note it was Abagail
that sent the letter in the Grandfather's name, not the Grandfather..