Thinking about the coming Northern Virginia winter and life in a 40+
year old house.

The attic has old fiberglass insulation between the rafters. Some of
it has settled in spots and it looks dried out and brittle if that
makes sense. If that doesn't make sense - well, it still looks dried
out and brittle to me....

Question 1: Would I get good bang for my buck by rolling out a new
layer of R-13 over the old insulation - but at a 90 degree angle?

Question 2: Would a vapor barrier make sense in the attic? Would it be
most effective under the insulation? Over the insulation? Or against
the roof?

Question 3: I have a gas burning furnace in the basement. The furnace
is in a room with the washer and dryer and in the winter, that room
gets pretty warm. The vent pipe exiting the furnace gets plenty hot.
Would insulating that pipe help keep the rest of the house warmer?