No single answer. Cough, chest pain, blood in sputim, shortness of breath, weight loss are all possible symptoms of lung cancer, but are not exclusive to lung cancer. As the disease can spread to other organs, headache, weakness or numbness may signify involvement of the brain, pain in bones may signify bone involvement.
Varies. Early stages, usually no symptoms. Late stages can include weight loss, coughing up blood, chest wall pain, headaches, stroke-like symptoms, bone pains, shortness of breath.