What does an individual's pain feel like with a herniated disc in the thoracic spine, thoracic herniation?

Usually no symptoms. Most thoracic disc herniations are not symptomatic. However if the disc is pushing any thoracic nerve, you will experience some pain around the rib cage at the level where the nerve is being pinching. If the disc is large and compress the spinal cord, then it may affect your balance/gait while you walk, and it may result in lower extremity weakness.
Tough to say. Thoracic spine is notorious for being difficult to pinpoint. The nerves have overlapping coverage in t spine. Usually diagnostic nerve blocks are required.