Drying time for wet insulation depends on type, ventilation, temperature, and humidity. If it doesn't dry within 2-3 days, it should be removed to prevent mold and wood decay.
Insulation should face the living space, with the vapor barrier (the paper or foil backing) towards the interior to help control moisture.
Insulation typically lasts 20 to 30 years, though some types, like fiberglass and rockwool, can last up to 50 years.