Defrost them in the frig over a few days. The sloweer thee better. Quick defrosting destroys cell walls. Good no salt Greek seasoning over low heat in either the oven or over charcoal and you’ll be happy.
Over indirect heat you’re probably looking at a couple to four hours (why God invented instant therometers). If you like a smokey taste soak some wood chips in water for a few hours before starting…add slowly on top of the coals as it cooks. Also let the meat come to room temp before cooking.