Legal Question in Criminal Law in California

Courtrooms in this country are open to the public except in very unusual situations (such as cases involving national security or trade secrets). Preliminary hearings in criminal matters are no exception.

And yes, the court will probably have other matters on the same calendar as the prelim. These matters may include preliminary hearings in other cases, as well as arraignments, motions, or other proceedings.

My experience with the Preliminary Hearing is that it will only be your case being heard (however, anyone from the public would be able to view). The Prelim is to determine if there is enough evidence to "bind" your case over for trial. If so, the next stage would be the Arraignment, then Pre-trial, then Trial.