Legal Question in Civil Litigation in California

Of course. Why not? Do bear in mind, however, that the law is clear that letters do not constitute "meet and confer." At a minimum a telephone conference must happen, and some judges expect an explaination of why telephone instead of face to face was used, if the discovery becomes the subject of a motion.

Sure.

Some judges actually require a knee-to-knee personal meet-and-confer. Typically, if an opposing counsel tries to stonewall on all discovery, it is efficient to put everything into one letter, separated by type of discovery. At the same time, though, it might be better to write separate letters to that, when a motion to compel is filed, not as much paper is generated.