Rain is really no big deal. The fenders will keep the dirty water off you. The rain itself is clean water , the kind you find under a shower.
A California rainfal is not likely to be cold, so it will just stop you sweating on the ride. Dress yourself in synthetics which handle water well, and and a breathable waterproof you wont even notice when you are wet.

Cleats: metal fitting which bolts onto the sole of a sport-cycling shoe. The pedal has a spring loaded catch to trap the cleat. It is called a clipless pedal system, because previously, cyclists bolted toe clips(cages) to their pedals with leather straps.
Toe clips are still widely used because you can ride in any footwear, but for racing and fast riding, everyone uses clipless.