When I'm preparing my make-up water before making wine or beer, should I boil it with the lid on (to minimize evaporation of the water) or with the lid off (to maximize evaporation of volatile contaminants, assuming there are any?)

It's cider brewing time of the year and I'm thinking of doing a cherry chocolate cider. My question is whether I should boil the cherries and chocolate nibs in a portions of the cider prior to pitching the yeast, just pitch the cherries (pureed) and nibs in the carboy to "soak" during the fermentation, or to use a cheesecloth bag during the fermentation. Each has its plusses and minusses. Any of you folk have some preferences or suggestions? I'm leaning …

I've got a bit of mold on top of my wort. My situation is a bit different than what others seem to have encountered... I made the wort about 5 days ago and hadn't gotten around to pitching the yeast. So my question is, if no known pathogens can survive in beer, does that apply in this case if the fermentation finishes?