You quickly learn to use the handbrake. With cars that have hill-holding feature, I bet it's much easier.

Many of the roads that pass through metropolitan areas can be bumpy; some can be very smooth. When you travel the roads in rural areas, they can be phenomenally smooth. Considering the vast network of roads that connects the cities, the majority of the roads in California are quite excellent, from my experience. Take for example Highway 1 along the coast. Or I-280 connecting Silicon Valley with SF. The roads for hundreds of miles south of the Oregon border are also incredible, smooth as the proverbial baby's bottom. And there are hundreds if not thousands of great sports car driving roads all over the state.
M-sport suspension is no problem for most of California roads, and is quite a popular option; maybe in run-down areas of LA (as in Detroit, MI, too) it could be a problem. A lot of M3's and Evo's here, and plenty of GT3's being driven daily as well.