Well, generally the cider pressers will either UV or heat pasteurize. In many places it's law. Ask. If they do it then don't worry about it. If they don't, then you should probably pasteurize it, I can't remember temps/times off hand right now, easy to find.
Someone else will have to recommend when to add the pectic enzyme. I've never done it this way. When you heat the cider it sets the pectin and can make clearing it a pain...
Or, you could try a natural ferment if it's not pasteurized. That could go anywhere from the best thing you've ever drank to toilet water, it's a lot more variable.