Here's my 2¢...

First, if you ever do have to shoot (or otherwise kill or seriously injure) someone outside your house, don't ever move them inside! Yes, you do have a better presumption of justified self-defense inside your home, but there's virtually no chance that it won't be obvious if you move someone. The primary thing you'll be depending on to keep you out of prison and keep from losing everything you own in a civil case is your credibility with the police, prosecutors, the judge, and jurors - the people you need to convince that you were acting in a reasonable and justified manner. If you are obviously lying from the start, that credibility, and your chances for anything like an outcome favorable to you in the least, just went out the window.

As to shooting someone in your house, you really need to study and learn extremely well the firearms and use-of-deadly force laws (including case law - the court decisions in deadly force cases) for your state. Anyone who owns or carries a gun for self-defense who doesn't do this is seriously irresponsible. Owning and carrying a gun is one of the most serious responsibilities you will ever take on, and not approaching it that way is the first best step to destroying your life, and potentially those of several others, including your loved-ones. While only addressing the laws of Florida, the best resource for understanding the laws of firearm ownership and use, and the use of deadly force is Florida Firearms Law, Use & Ownership; by Jon H. Gutmacher. It's a good start for anyone who wants to understand the nuances of the subject, though if you don't live in Florida, you absolutely need to find out how the law is different in your state!

In every state, the minimum standard for the use of deadly force for self-protection is a reasonable belief that the threat of death or serious injury is "imminent", where "imminent" means about to happen right now. The differences are in what constitutes reasonable belief. In some states (those that require you to attempt to retreat), your belief that the threat is imminent is not considered reasonable, even if the threat is obvious (a burglar with a knife or gun, for example), unless and until you have evaluated and exhausted your options for escape (it should be obvious that this is a recipe for unreasonably and needlessly turning a lot of people into victims - the old line that if you just give them what they want, they won't hurt you, is patently false, as demonstrated by countless cases where the victim is killed or injured after cooperating).

In other states, particularly

those that have "Castle Doctrine" or "No Retreat" laws (including, by the way, California), you are not held to such an unreasonable standard, at least not in all situations. Despite the rhetoric, these laws do NOT give you the right to escalate or pursue a confrontation, they simply remove the absolute requirement that you make an effort to escape before defending yourself. You, as the victim of a violent crime, are given the presumption of innocence in self-defense cases, unless it can be shown that you indeed used unreasonable force (in other words, you're given the same assumption of innocence that every other person facing criminal charges has always had, instead of being assumed guilty if you defend yourself against violent criminal attack, which is what states like Illinois do to its citizens). In many of these states, your belief that a threat is imminent is now automatically assumed to be reasonable in certain situations. For example, in Florida, if someone "unlawfully and forcibly" enters or attempts to enter an occupied lodging (even a tent) or vehicle (such as during a burglary or car-jacking), you are automatically entitled to reasonably believe that they are an imminent threat, and act accordingly (with certain exceptions - like law-enforcement or cohabitants). This means you no longer have to wait until an armed burglar has you trapped with no chance of escape before you shoot him. These laws also generally protect you from civil prosecution if your actions are ruled reasonable self-defense.

As to the use of force outside your house, you are still entitled to defend yourself against imminent threat using reasonable (even deadly) force, even in public. The only thing that changes is that you are under more of a burden to show that your belief was reasonable in how "imminent" the threat was (while you might reasonably believe the home-invasion robber who just kicked in your door is an imminent threat even if you don't see a weapon, the guy at the ATM who demands your money, but who is not obviously armed, might require you to attempt other options before resorting to deadly force). Keep in mind though that the use of deadly force is never a simple or trivial thing. Even if you are completely in the right (let alone if you just "believe" so), you could still lose everything (a man in Florida who was recently acquitted in the use of deadly force still lost everything he owned due to legal expenses and spent 8 months in jail during his trial - even though he is free and now immune from civil litigation) or even go to prison for the rest of your life. But as was posted earlier, it may be a choice between "judged by 12 or carried by 6". Besides understanding the law to the best of your ability, if you own or carry a gun for self-defense, you had better carry the number of a good lawyer who specializes in gun and self-defense law on you at all times.