Follow the gas line from your meter if its in basement and see which furnace it goes to could go to both but its doubtful.I have ran across ductwork that a clown didn't install right and someone was getting free heat and air in a bedroom and bath.

I would imagine, given the building's age, that it would need to have the duct work put in to accomplish this, which would have a steep price tag.  

On another note, as FYI, the coffered ceiling is likely a capitalized consequence of creating the open floor plan and adding central HVAC... concealing a dropped beam(s) perhaps, to create the openness, and at least in the Kitchen area, it is concealing ductwork.  

If you have duct work, make sure the ducts are clean and the air registers are not blocked.

Hi so my duplex that I just bought needs an upgrade with the HVAC unit, I am replacing the window unit and electrical radiant heat with a central ac, i got a bid for 7.5k wanted to know if that is a good bid for new HVAC unit, duct work, heat pump and installation?

Some furnaces have the cooling coil inside the furnace, sometimes there is an AC cooling coil installed in the ductwork downstream of the furnace air handler.  

. $9k for both sides is not outrageous, however it's a tad steep for Florida - unless there's copper replacement, ductwork, etc.

Any Milwaukee landlords have an idea the cost range of running furnace ductwork to an upper flat?

You can add central heat and air, but it will be very expensive because the you have to add all the duct work.  

Sometimes there are dampers (I think that is what they are called) that can block warm air from going down some legs of the ductwork.