DD4 swims twice a day at summer camp right now (once during the day and once for swimming lessons). I normally rinse out her suits then let them dry. Sometimes I have to give them a quick spin in the dryer in the am snce it is so humid here.
As for her hair, after her bath at night, I put a spray on conditioner/detangler in her hair, then while it is still wet, I braid it into two pigtails (much like Laura on Little House on the Prarie). She sleeps with it like that, then swims the next day. When she comes home, I take the braids out for a couple of hours, then start all over again at bath. The braids really help minimze the tangles that can get into long, thick hair when swimming. I will do something similar at WDW this summer.