Hello @Jack B., I have been a home builder and still sub out my work on flips or rentals for investors, so I have a lil experience in the matter. My strategy hiring roofer or any other sub contractor is buying my own material and just get a labor price. Regarding roofers, get with the roofer you mentioned you want to use and get the company he uses to buy to buy shingles. Ask the company rep how many roofs or how much material he uses, how long hes been buying, does he have credit at that store or does he pay cash, and does he pay on time if uses credit. Also ask if the roofer picks up own material or they deliver it and who loads the shingles onto roof. I ask these questions cause it will tell you a lot about that roofer. As far as contracts and deposits, use the standard service contract spelling out whats included. If only labor, then there is no need for a deposit. You also need to pay for nails, flashing, felt, drip edge, pooky, ridge caps, decking, vents fireplace flashing if any. You will find when you pay for all material, you get the warranty from the manufacturer and you get to keep left over material for another job. Those turn key guys like to keep. Sometimes its about $2-400 or more. If you have general liability insurance, paying only labor decreases your annual costs. Get references and if they do insurance work, get that insurance rep reference. Its best if they are bonded, have insurance and licensed. Get copies if willing to give you. And at worst, should warranty their work for 30-90 days. If they are good company, they should have 4-6 guys working on roofs. 30-40 square 8/12 pitch roof shoud only take 5-6 hours to tear off and put new on. Sorry for being wordy, but this should answer all your questions, at least from someone who's ran a company with some street sense. Good luck.