|Electrical in Orlando, FL
Though a standard question, it's important to ask. Most contractors will tell you how long they expect the job to take without you asking. If they don't volunteer that information, be sure to ask. It's also helpful to ask if that's a hard finish date, meaning that it's the definite finish date. If it's a soft finish date, it may be extended for any number of reasons.
You'll certainly want to ask them this. Steer clear of any company that is not insured in Florida, because that means that any incidental damage they may do on your property will be a real hassle to recover compensation for. It is never wise to work with uninsured tradesmen of any kind. Most states also require that someone have insurance in order to be issued a trade license. If they say they're licensed but not insured, they're being less than truthful.
These first two questions should only relate to services or good purchased directly from the service provider. Many products carry their own warranties, like roofing shingles or siding. It's useful to know what these warranties cover as well as how long they last. The "warranty agent" question is important, because often warranty agents work with the manufacturer to get you repairs under warranty at a much lower price.
This is very important, since an estimate is just that. Many contractors will submit a "paper estimate", meaning they've written the estimate down on paper. The bill is the true amount owed and will almost always say "Invoice" or "Bill" at the top of the page. The bill should also list the date it was issued, the due date of payment, and a list of services rendered.
Some companies may require a 10% deposit, some may not require any. For larger projects, you'll almost always need to give a deposit, and it's good to ask how much the deposit will be before going forward with a project. The Orlando contractor will know how much they need for a deposit when they've given you the estimate, so ask early.