It's okay for the Fashionista prong to turn light pink, that's where the plastic stretched. They can withstand a head swap or two, just don't make a habit of it. Of all my head swaps I've only broken one arm of a prong but the head still went on.
What ever you do with head swaps don't dunk a doll with a painted face or complicated hairstyle. A hot water dunk is a great way to give a perm, braid or twist the hair, put in place with little rubber bands and dunk or poor the water over the hair. Let cool and air dry before you take the hair down, don't use a hair dryer to dry the hair because it will mess with the texture.