Answers

In regards to roofing, Owens Corning has a great checklist and you can find it at the link below! Here are just a few items to check though: 

-Accredidation and good standing with the BBB

-Additional Warranty and Workmanship Coverage

-Verify how long they have been in business

-Addequate Insurance (at least $1,000,000 in general liability insurance) 

-Code Compliance

-References 

-Quality Materials 

owenscorning.com/storm

http://www.jeffroof.com/blog/what-to-look-for-in-a-contractor