Is the contractor licensed in Mississippi? Are they a "shadow" contractor (not local, but working under a local license)? If they are not a local contractor, who will provide warranty repairs after they have left the state? What is the contractor's reputation? With no license you have little recourse. Without proper insurance you become responsible for any accidents on the property.
What references can the contractor provide and how far back can they provide them? A contractor should be in business at least 3 years. Good references over a longer period indicate the contractor is interested in maintaining and gaining new customers in the area.
Does the contractor:
1. Thoroughly inspect your roof? Inspection should include flashings, chimney, soil stacks, any and all other roof penetrations, roof deck, plus attic and ventilation.
2. Provide a written estimate for all work anticipated?
3. Use quality roofing materials and explain the manufacturer's warranty for defective shingle?
4. Know and comply with local building codes?
5. Explain reasons for removing old roof versus nailing over the existing roof?
6. Use six fasteners in high wind areas?
7. Use sufficient length fasteners to penetrate 3/4" into deck?
8. Supervise the job during all phases and inspect it completely when finished?
9. Thoroughly clean up your roof and around your house when finished, and remove materials?