A deductible is an amount that you're responsible for in the event of a loss. This is the amount you pay out-of-pocket, and insurance covers the remainder.
When speaking with your agent to set up your policy, be sure to mention any valuables you are concerned about so the agent can review your policy and recommend changes to ensure your valuables have proper coverage.
It depends! Most homeowners insurance policies cover water damage that was sudden and accidental. Water damage due to flood is covered by a separate flood insurance policy, not the standard homeowners policy.