The answer is simple. Any further discussion will turn this into a gun control issue.
NOBODY KNOWS.
With regard to any kind of criminal prosecution, that is up to the local prosecutor. It isn't up to the police, although they may or may not make an arrest on the spot. Only the prosecutor can take it to trial, and there is no one reading this board who is inside of the mind of our local prosecutor.
With regard to any kind of civil action, anyone can sue anyone for just about anything. Any of your scenarios would end up in the hands of a jury, and there is no way anyone can really predict what a jury will do. (Remember that a criminal trial jury acquitted O.J. Simpson and in a later action a civil jury convicted him on the same facts.)
I was once in Federal Court for the trial of a man accused of forging a government check. The defense attorney addressed the jury and admitted that his client forged the check. Then he offered the defense that his client was an alcoholic. The jury found him Not Guilty. Not Guilty??? His attorney admitted he did it. The jury should have found him guilty and left it to the judge to take the defendants alcoholism into consideration in the sentencing phase.
By the way, if the little old lady hit the bad guy with her shot she would still be at risk for both criminal and civil actions.
No one can give an informed answer to your hypothetical scenarios.