The reliable way to hire a pro

Last year, I hired a roofer to redo my roof and install a skylight. He promised to send over the paperwork but it never showed up. Now, a year later, I'm trying to sell my house and my buyer wants those documents. The roofer is still dragging his feet on giving me the paperwork or any guarantees. All I have is his phone number. Is he supposed to provide this and do I have any rights to insist on it?

Do we need a plumber to see if a dishwasher can be repaired?

I need to replace shingles as a cost saving measure is it okay to leave the old ones on and just put another layer