Here's a good web forum for california.

http://www.calguns.net/

At the store you'll take a written (multiple choice) gun safety test. Its about around $25 or so and is good for something like 10 years. For storage, if your safe is not on the CalDOJ list of approved gun safes you're required to buy a gun lock (if it doesn't come with one.) Also, you can only purchase one handgun every 30 days, and you must wait 10 days after purchase and filling out DROS paperwork to pick it up. Oh, and you must bring either your car registration with current name/address or a recent gas/electric utility bill.