3. One shot, target goes down.
Bruce, this won't happen. I don't care if it's a .50 cal Barrett, unless you make a perfectly placed shot, it's not a guarantee.
Having said that.....what follows is my opinion. It's worth what you paid for it......
Shotguns; the point here is that this is NOT a "spray and pray" weapon. At typical home defense ranges, you can miss quite easily. That, and they are larger / harder to store / lots of recoil put them low on my list for home defense.
1911 model pistols; in the hands of an expert, these are probably one of the most effective, most lethal weapons for close range defense and denial on the planet. Problem is, they are really an "experts" weapon. 1911's (other than the esoteric Seecamp and a few others) are "single action" guns which means the hammer has to be back or the weapon won't discharge. For a person that's not trained and expreienced with this gun, in the heat of the moment, you could pull on the trigger till the fat lady sings and the gun won't go off....unless you remember to cock it first. Storing this weapon in the "condition one" state (cocked and locked) is something that many folks aren't comfortable with. If you're willing to put the time in to learn these guns inside and out, these are the cream of the crop but make no mistake - there is a downside to these pistols. Your call there......
Glocks; I'm partial to Glocks, and own several. They are rugged, dependable, reliable, and damn accurate guns that will shoot and shoot under the worst of condidions and is spite of less than stellar maintenance. However, Glocks, like any autopistol, require some additonal manipulation to be effective. If you're going to go to the range once a month or so (and you damn well should if you're going to keep a weapon for self defense) then the Glock is an excellent choice. A Glock 23 in .40 cal with a Streamlight light / laser on the rail is my "things that go bump in the night" weapon.
Lastly, the relvover. Truth is, for a first gun, this is what I highly recommend.
I have one of these. The Tarus is a Smith and Wesson clone, made well, and with a lifetime warranty. Reasonably priced. You can take that .357 to the range, and shoot .38 specials in it until you are very comfortable, and then shoot full house .357 ammo as you like. You can buy defense ammo for a .357 that is as effective as anything there is. A revolver is easy to shoot, easy to understand, safe, and just an all around great gun. I would give this serious consideration.
Lastly, you need to take some classes. Find a local range and sign up for some pistol classes. And, practice. Practice more. Practice again. Shoot AT LEAST once a month, and should the "worst case" ever happen, you'll be ready to defend your family safely and effectively.
PM me if you'd like to chat....glad to steer a brother down the right path.
Best Regards - B.B.S.