Is pulmonary edema a sign or symptom for pneumonia?

No. Pulmonary edema refers to fluid in the lungs, whereas pneumonia is an infection in the lungs. They are different entities, although sometimes they are difficult to differentiate.
Neither. Pulmonary edema is fluid in the lungs, while it can look similar to pneumonia on chest xray its really a different disease. Sometimes severe pneumonia can cause a disorder in which fluid leaks into the lungs, this is called the adult respiratory distress syndrome, so in that sense a kind of pulmonary edema can be caused by pneumonia. More often pulmonary edema occurs when the heart is impaired.