No one likes to think about the legal aftermath of these things. Let me summarize a few of my beliefs:
-If you go sweeping your house, you are in a weaker legal position than if you get behind cover in the bedroom and call 911. If you have kids to secure, have a plan where you all meet in the same place, then get behind cover and call 911. Let the police do the sweeping and shooting, you shooting is a last resort.
-Shotguns are less legally taboo than handguns. Anyone can buy a shotgun without a permit. I'd rather defend shotgun use than handgun use (but would certainly use whatever was a better tactical choice, regardless of legal outcomes). This is just an opinion, I feel like a DA would be less likely to take a questionable lethal force case if a long arm was used vs. a politically scary handgun.
-Firing one shot is better than firing many. Fire until the threat is neutralized, but techniques such as "two to the chest and one to the head" suggest intent to kill and not intent to neutralize the threat. For all you know, the threat would have been neutralized but not dead after one, or two shots.
-Use a flashlight. There's no reason not to (you can mount it on your handgun OR shotgun, or use it independently of a handgun). It is negligent to not identify your target before opening fire.
-Calling 911 should be your TOP priority unless your life is in immediate danger. The first person to call 911 wins a huge battle; you don't want the intruder who you just shot to be the one calling 911 on YOU. If you call 911 before you shoot anyone, you demonstrate that you did not want to use lethal force and did everything you could to avoid doing so (the police weren't here yet). Be sure to identify yourself so when the police come in guns hot they know which guy with a gun is the good guy.
Kathy Jackson (pax) said in her book (and I'm paraphrasing), the only real victory here is if you escape with your entire life intact, and that is not achieved if you spend it in prison or even a large part of it in court.