If overflow tank level is going down then you have a leak.
Rad will always be full if there is coolant in the overflow, it sucks it out of overflow tank to replace any leaked coolant, that's the system design, it is doing what it is suppose to do.
Passenger side of engine is most likely a heater hose connection.
They can get pinholes and coolant sprays out in a very small stream.
If you have air conditioning then there will always be water dripping on the ground on the passenger side but nearer the firewall than engine, but certainly by the frame under the firewall
It is normal for engine to take awhile to cool off.