Heavy phlegm comes out when I cough. Does this mean that I have poor lung health?

Not necessarily. Sputum production can come from postnasal dripwhich normally results from allergies. Also, some patients with sputum have gastroesophageal reflux disease. From a pulmonary standpoint, many patients with a variety of respiratory disorders complain of sputum production. To be sure what's causing the sputum, I would recommend a full history by a physician.
Possibly. Could be bronchitis, or could be pneumonia. .. Or could be bronchiectasis resulting from either. .. Consult with your doctor for lung exam and chest x-ray, possibly also ct scan. ..