Oh, boy ~
You neglected to tell us where you're located but in any case, puddles on the carpets almost always mean heater core leaks, this can be serious as it's a major job to change .
OTOH, if or once, your cooling system is squeaky clean you can often use "Silver Seal" to plug the leak and not the radiator .
My 1980 300CD had thick red sludge in the entire cooling system when I bought it, I had to replace everything (!) including the exterior coolant transit pipes, thermostat housings, hoses, valves, FREEZE PLUGS
on and on, one it was all done the heat was fine but after six months I began smelling coolant then noticed some coolant in the passenger side foot well .
The long and short was : the heater core was too rotten to hold the coolant under pressure .
Instead of taking the ENTIRE DASHBOARD APART I added one tube of Silver Seal and a 1949 Chevrolet radiator cap ~ that cap isn't pressurized yet the car never leaked again and didn't overheat when running it flat out in Death Valley with the AC on in 120* F heat .
No matter what else you find wrong, you're going to need to address that coolant leak first and foremost .
Don't panic and don't give up just yet .