Some good stuff here, but a few points------------
1.) "Stopping power" in cartridge to cartridge comparisons is one of those things that is a lot more crap than anything else. Don't get me wrong, a 357 hits harder and does more damage than a 38 special, but any of the normal, service grade calibers (9mm, 38, 357, 40, 45, and yes even 380) will stop someone IF you hit them in vital areas. In the movies, guys get hit with a 45 and go flying back. Want a fun test? If you have access to an outdoor range (and I'm speaking to all of you who are going to try and hurl ft-lbs. numbers at me), cut a slice in the top of a pumpkin and slide a 1/4" steel plate down into it. Place steel-cored pumpkin on a raised surface like a stool. The steel is there to absorb the bullet's energy and not let it just punch through the pumpkin, the pumpkin is there to catch the debris/ricochet. Now, shoot pumpkin with handgun of your choice. Watch pumpkin roll or fall off of the stool. Notice that the 15 pound pumpkin and plate DID NOT fly off the stool. Now ask yourself if the same bullet would send a 200 pound man flying. So drop the thinking that you don't have to be as good with a bigger caliber because it'll stop them if you just hit them. A 45 through the deltoid is not a fight-stopper, a 380 in the heart is. How well the gun fits you and how intuitively it points for you are the main factors to consider. From there, if you're comfortable shooting a larger caliber and can do it well, great. If you have to go smaller to do it well, go smaller.
I worked in a gun shop once as a rangemaster, and between that and military time I've seen a whole mess of people who get wrapped up in the magazine-reading, latest and greatest type of thinking with their firearms and ammunition, and never spend the time to actually get good and putting bullets where they need to be put. Being able to stand comfortably in an air conditioned range with a well lit target, no pressure, all the time in the world, and hit the bullseye has absolutely nothing to do with being able to hit something when you NEED to, especially if it's moving or fighting back. Once you get the fundamentals down, you need to practice point shooting and getting on your target fast---they're not going to stand there calmly while you get set up.
2.) If you go for a handgun, don't worry about capacity. If you like the feel of a pistol better than a revolver, or the other way around, then let that be your guiding decision. Again, getting some training should give you the opportunity to try different things out, and you'll start to understand what feels better to you. Defensive shootings are usually over in a couple of seconds with two or three shots. Being the one to get those shots off first, quickly and on-target, is what wins. The prolonged, running gunfight stuff (outside of some police or military situations) is only in the movies. Assuming it actually did happen: I don't care if you have 10,000 rounds in your magazine, if you're facing a whole room full of armed opponents by yourself, you're going to lose. If you can't hit anything and try to take comfort from the fact that you have 15 shots to get lucky with instead of 6, you're going to lose.
3.)As others have said, it's not about WANTING to pull the trigger, but if you feel you can't, then don't have the gun. However, nobody has detailed why. You have no idea what the intentions are of a person who attempts to attack you or invade your home. May be a murderer, may be a rapist, may be a guy looking for a free TV who is going to run at the first noise he hears. It could be a life or death situation, or maybe not. However, once you introduce a gun into the equation and he (or she) sees it, it now
absolutely is a life or death situation as far as the intruder is concerned. The intruder is not going to be thinking, "Maybe he's just trying to scare me." He's going to be trying to save his own life. His eyes get wider, his blood pressure increases, his adrenaline kicks in, and exactly one of two things is going to happen: he's going to move very quickly, either away from you or right at you. If he runs, great. If he doesn't, whatever his intentions were when all of this started, he's trying to kill you now to save his own life. If he has his own weapon, he'll go for it, if he doesn't, he'll go for yours. If you know in your heart that you can't use deadly force, then DO NOT escalate the situation in this way.
Again, it's not about wanting to kill someone. I'm CPR certified (and get re-certified every two years) and have never had occasion to try and keep anybody alive. I hope I never have to. But, if I have to, I'm willing.
4.)As others have said, if there are kids in the house, the whole family needs to be a part of this. I was taught gun safety and to shoot starting when I was six years old. I knew where the guns were, including the loaded one, and honestly never touched them without my parents around. By the same token, I knew where the stove was, how it worked, and never cooked myself. Your kids watch every single thing you do (they're programmed to do that so they can learn how to be) and you're absolutely not sly enough to keep this a secret from them. If you don't let it be a mystery, however, you'll take away the "I must get to that thing" fascination. If you make it Bluebeard's Chest, it'll become a quest for them.
I'll probably piss somebody off by saying this, but it's kind of the same thing as parents who can't face the thought of their kids knowing about (let alone having) sex, and so trying to pretend it doesn't exist or make it a taboo. They're GOING to find out from somebody, so you do best to take an active part in what they learn.
Done correctly, and safely, it can be a very fun family activity. Shooting, not sex.
