What symptoms can a benign lung nodule cause, and whether it causes blockage and effect on breathing?

Mostly none: In general, lung nodules benign and malignant are asymptomatic (without symptoms). That said, benign is more likely associated with infection. Thus symptoms such as infection and pneumonia may be present; fever, cough, etc.... Other symptomatic nodules may be from sarcoidosis. There is a large list of symptoms with sarcoid.

Mostly none: Almost all benign lung nodules were found by accident, xr for other reasons. They are usually small and not cause any symptoms. If they are large and or growing, we say they ae not benign.