<p>Personally, I would like to see such questions on CrossValidated. (But I may be biased.)</p>

<p>However, this particular question asks 4 questions in one. So either there will be partial answers, or it needs to be split. </p>

<p>Also, for such issues we need to be very clear (a label like for cigarettes?) that "correlation is not causation" not to make people think that the results mean sth more (or even worse: that we have scientifically proven that weapon (not-) ownership makes someone life longer". This obvious for people here may not be for the general audience.</p>
