No, phosphorus is NOT in glow sticks. Phosphorus is way to dangerous to be put in glow sticks. While a glow stick does have phosphorescence (meaning glow after illumination), it does not have phosphorus.
Glow sticks are fun to play with you just take them out of the package and then snap them until they glow. But if you break the glow sticks then they will get on your friends night gown that you borrowed and then they will glow too.
No, glow sticks don't last forever. They have a limited life, and it will depend on the stick. Some last for a few minutes, and others last many hours. Size, construction, chemical composition and temperature will generally set the length of life.