Hole in the nose
it is to cool the drivers feet, as they sit right behind a big hydraulically assisated steerign rack, there is a hole in the front bulkhead for access to the dampers and to connect the steering column to the rack.
People without power steering (i.e. Sauber) do not have these holes. Other teams also put ducts in the access panels on top of the chassis to further cool the driver and BAR had little NACA (NASA or delta shaped) ducts in the head restraints, these fed cooling air down behind the seat for both the driver and some ECUs.