How long should a fever associated with strep throat last?

It depends. Fever is one of the body's way to fight off infection. Strep throat is a bacterial infection that needs to be treated with antibiotics. Generally, fever resolves within 1-2 days after starting an antibiotic for strep. If it lasts longer or is other symptoms persist for more than 4-5 days, check back with your doctor.
Depends. When treated it should respond within 48-72 hours. It usually responds quicker to penicillin based drugs than some others. If untreated it could persist for a week or more before the bodies immune response fought it off. The raging fever of "scarlet fever" was a well known strep related disease in the era before antibiotics.