1. White hat -- when it starts to yellow around the bill; black hat -- when it gets relatively icky on the front of the band. So usually twice a year for the white hat and once a year for the black hat.
2. I let it soak in a large pot with Oxiclean for a bit, and then use a toothbrush to scrub away the dirty parts. I have a hard plastic protector that the hat fits over. After washing it, I put the protector in and set it on my dryer. It dries in a day or so and the protector keeps it from shrinking.
3. I have Richardson fitted hats, and I've had them for probably 10 years.