These are complex questions. The company should be licensed by the Tennessee Department of Agriculture. As with any service company, references are invaluable. Consider calling at least 2 - 3 companies. Requesting inspections and estimates from more than one company will substantiate the extent of your termite problem and allow you to compare services.
Companies offer different types of warranties or service agreements.
Most offer retreatment of localized areas if the termites return. Take your time when selecting a company. Ultimately, the quality of a termite job depends less on the person who sells the job than on the individual who does the work. A safe and effective treatment requires a trained qualified technician. Another complex and difficult question.