Is it possible for radiator fluid to be leaking inside the passenger side of the car- maybe even thru the A/C?? I can't see any fluid on the ground under the car. There is definitely fluid on the floor board of the front passenger side of the car.

 

Yes, coolant can leak inside the car.
Your heater core is leaking and needs to be replaced.
When you turn on the heat, you should see the glass start to fog up.

Heater cores require the dash to be pulled out.
Never a fun job.