My goodness. Take it easy on the guy. He's not quite so sure about his methods, wherever he may have gotten them from, and he's coming here for better advice.
You don't even have to kill them, just drop them in the screamingly boiling water (Julia Child did it that way so it can't be wrong), or you can jab them just behind the head w/ a Chef's knife in the nice crevasse of their shell. A fraction of a second, lights out.
Now as for cooking times, here's an "IDEA", not gospel carved in stone:
Boiled : 1 lb. : 12 - 15 minutes / 1-1/2 lbs. : 15 - 20 minutes. / 2-3 lbs. : 20 - 25 minutes / 3-1/2 - 5 lbs. : 25 - 30 minutes
Steamed : 1-1-1/2 lbs. : 20 minutes
Grilled Whole *(pre-cooked) : 1-1-1/2 lbs. : 2 - 3 minutes
Grilled Tails : Each : 5 - 7 minutes
Broiled Whole *(pre-cooked) : 1-1-1/2 lbs. : 3 - 4 minutes
Broiled Tails : Each : 9 - 10 minutes