Mike
The fronts on an 8 wear faster because they don't have enough camber adjustment from the factory. If you flog them the outer edge of the tread frays quickly.
The rears have it a bit easier with more camber and not enough horsepower to hurt them badly.
The shutdown sequence on an 8 can take up to 15 minutes. But the heater fan should shut off with the key. Push the TIMER button on the OBD and see if it says ventilation off. If it doesn't then one of the vent timers may be on. Usually the bright led in the timer button is on if autoventing is activated.
If you look in thru the windows, the odometer display is the last thing to go off. Should be off in less than a half hour max. Opening doors or the trunk starts the wake up.