How fast can pain cause damage to gallbladder?

Depends. Gallbladder disease is a spectrum from acute inflammation and infection to chronic, recurrent inflammation. If the gallbladder "out-track" or cystic duct is completely blocked and is not relieved it can turn into an infection in less than 24 hours.
No relation. Pain does not cause damage to the gallbladder. Damage or inflammation of the gallbladder can cause pain however. Some people have intermittent pain for years. Best to see a general practitioner for a consultation to find out if indeed there is a gallbladder problem. Usually need some blood work and an ultrasound as well. Hope this helps!
Difficult to say. If pain is caused by acute infection, damage is pretty rapid. You need to have immediate surgery. If it is caused by colic, then it can vary with severity and frequency. If you are having ANY symptoms from gallstones, it is best to treat with elective cholecystectomy, before complications such as acute cholecystitis and pancreatitis develop.