Fertility and hatchability are two seperate issues. You should be able to check fertility by candling the eggs. Embryo\'s should be very evident by 7 days of incubation, and with practice and experience some can tell within 4 days. It will depend somewhat on the density and type of blue or brown pigment in the shell. If both blue and brown are present it will be more difficult. White eggs would be the easiest.
Hatchability depends upon a multitude of factors, including breeder hen diet, health, storage temps, humidity, etc.