Good luck with the
double layer of 5/8" plasterboard on the ceiling. At least you can rent a
drywall hoist to raise it and hold it in place while you screw it off. I don't
envy you the task...that's why I always hired that job out.
The fire door is a question that local building codes must answer. Since I
almost always was working from plans and specifications developed by
architects, I just did what was called out. I think that 20 minutes is all that
is required in residential work, but it could be 1 hour. I can tell you that in
my house, the door between the garage and the living space is a molded solid
core exterior (1-3/4") door. By molded, I mean that it is masonite on the
outside with particle board inside. It is moulded to appear as though it is a 6
panel door.
You should find that a door retailer (or wholesaler) can give you
specifications on any door, including the fire rating. When the door is hung it
will need to have weather stripping that can keep out smoke or car exhaust. The
door will also need some sort of self-closing mechanism. This is usually
handled with spring loaded hinges.
I can't say that I have ever installed a fire door that had a window in it. You
should ask the door people about that one. Here in the Seattle area I still
recommend Frank Lumber, "The Door Store".