It all depends on social context.
1. & 2. When I am alone, I care about the same for serial killers as I do anything else, which is not a lot encroaching on none at all. I find the "portrait" of a sociopath to be just a cookie cutter as any other stereotype, but alas, there are reasons stereotypes exist. Regardless,
When with my "rocker" friends, or other friends I know who seem to have a fixation with serial killers, you bet your ass I find them cool as fuck, and enjoy all the little banter and shit. Though this is rare, it does happen. I attribute this to the "It's easier to have friends than enemies." technique. Why would I disagree when I can agree and you'll like me slightly more? Even that variates with context, but ANYWAY,
When with family it's typically something watched on T.V. considering television companies are obsessed with serial killers and sociopaths now. There is a channel dedicated wholly to murders that I see constantly referencing sociopaths. I seldom find theses shows interesting, though.
3. Mostly I don't care. Although you would have to be an idiot to think that sociopaths craving the thrill of the kill are not out there, they do not make up the majority. The few diagnosed socio's I have met have been fairly good "seeming" people (a wolf in sheeps clothing) and I had no troubles dealing with. One I actually got along with fairly well.
Just as with anything else, there is a lot of misconception and stigma, but that cannot be avoided as not everyone will put in the time to discover that not all sociopaths are out to kill at all. I have nearly no prominent violent desires, but I sure do enjoy pitting people against each other and breaking hearts.