Megan Fox is no slouch, but if you pick the 25 prettiest girls you know, turn them over to Megan Fox's hair stylist, makeup artist, wardrobe stylist, and image consultants for a week, you'll know at least 24 girls prettier than Megan Fox. Same is true for pretty much any celebrity you can name. Celebrities aren't inherently more attractive than "average" people. They just have the resources to polish what they've got.
All the time. Most female celebrities I see aren't that hot, and I'm not going to find them more attractive than non-celebrity women just because the entertainment industry wants me to be infatuated with them. There are a couple women in my class and a couple nurses at my work that I would date before Megan fox.
Pretty much everyone. Most celebrities aren't particularly talented or attractive and thus there's no reason to revere them as some kind of God. Our celebrity obsession is a sad indictment of what is a rather primitive species known as humanity.