Failed gasket, seal, hose, freeze plug, radiator.......
cap is off
water pump
You would have a leak, from either the pipes to the heater matrix (radiator), or the matrix itself.
You could have a bad water pump gasket.
It probably has a leak, possibly from the heater core.
The car will over heat.
there might be a leak some where in a coolant line. or maybe you have a leak in your radiator.
The water you see under the car when the air conditioner is running is condensation. If you are leaking antifreeze then you need to pressure test the system and repair the leak.
It depends on how bad the leak is .If its a really bad leak to the point where the car is starting to overheat then no
Check for a line leak to your heater core or a leak in the heater core it self. Usually it is under the dash on passinger side.
You have to determine the source of the leak then decide on how to fix it.
You normally smell the antifreeze so open the hood and look for a leak before you see it big time running out from under your car.