If I get radiation and chemotherapy for my esophageal cancer and have clean CT and pet scans, will I still need surgery?

Maybe. Therapy for esophageal cancer is dependent on the stage. There are IV relative stages. In the physically fit patient, the upfront therapy for stage I and iia is surgery. For stages iib and iii, the therapy of choice is chemoradiation followed by surgery. For stage iv, chemotherapy +/- radiation and no surgery. That being said 15-20% have complete eradication of tumor after chemoradiation.
Possibly. That is the big- time question now. The only way to know the cancer is resected is to examine the specimen. Todays imaging studies will give some information, but are limited by post- therapy changes. Repeat biopsies only help if you identify the right area. Observation may be possible, but surgery gives more consistent results.