With the roofers, be sure to verify two things: (1) look at the roof shingles they bring and _make sure_ that they are good for the number of years you paid for. Roofers slipping you 15 year shingles when you paid for 20 year shingles is a thing! (2) make sure they put down the black asphalt vapor barrier on the roof before they hammer in the shingles. They must also replace any rotten wood in the roof with new boards.