In a nutshell - the jobs are extremely tight. Major roles are usually cast in Los Angeles, but the smaller roles are cast here. You have to run the gauntlet of audition and numerous callbacks. The decisions are made by the casting director and the particular director of the episode. The NB interior sets are located on the Treasure Island facility inside the aircraft hangars.
Exteriors can be anywhere in the Bay area.
We've always admired actors for their commitment to their craft. It's difficult to make a living in television alone, and many are involved in theater, commercials, and industrial video. If anything we've described is discouraging you from acting, then you aren't for real and you don't love acting enough. From Jerry Carroll's SF Chronicle column of April 1st comes the report that sportscaster Ralph Barbieri badmouthed Don Johnson on a radio morning show. Barbieri noted that Don shows the worst Hollywood traits, such as having a flunky there on set just to hold his coat.