Lesco Electric

You'll certainly want to ask them this. Steer clear of any company that is not insured in California, 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 will be answered when you ask if all employees are licensed. The only way to obtain a legitimate tradesman's license is to be a legal or naturalized citizen of the US. The company may employ people in positions that don't require a license, however, so it's wise to inquire.

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 Valley Center contractor will know how much they need for a deposit when they've given you the estimate, so ask early.