I've learned a few things from riding my bike in California.
The laws can be kind of strict and sometimes contradictory, but for the most part they aren't unreasonable. Just a little hard to abide by without spending some extra cash. If you're just riding your bike around a neighborhood, I wouldn't suggest spending the extra money on lights, turn signals, registration, etc. If it's just a toy then just treat it that way, and the possibility of getting in trouble will be extremely remote. Using your bike to commute, on the other hand, requires the same things that other vehicles require.
Most importantly, though, most cops aren't out there to nab people for itty bitty parts of regulations; they're just looking to make sure that you're being responsible and not putting yourself or others at risk. As long as you've got your lights, your DOT helmet, your plate, and you're not driving like a maniac, then the most the cops will do is pull you over to just ask you about your bike out of curiosity. There will be exceptions of course, but in general, most cops aren't that petty. They're people too, and the might even think your bike is cool. Not all of them, since some cops are trashy a-holes. But generally, cops are alright as long as you're being responsible.
EDIT: It's one thing to be mad at CARB/EPA for draconian regulations making 2-strokes hard to get, but California motor vehicle laws aren't that hard to abide by.