What is the best treatment for esophageal problems from lung cancer radiation therapy?

Several different. Radiation can cause inflammation and irritation of the esophagus which can lead to secondary fungal infections. Long term it is possible the esophagus will develop scar and feelings of food getting stuck. Remedies include liquid medicine for inflammation and fungal infection. For strictures endoscopy with dilation. And of course pain medicine is always helpful.
Depends. The esophagus may receive doses of radiation that can cause inflammation, pain, strictures and fibrosis. Depending on the time course during or after treatment, your radiation oncologist (or GI doctor) will be able to help you with these side effects or complications. Pain medications, cytoprotectants, diet modifications, anti-acids, etc, can all help with short-term swallowing problems.