I wanted to answer your question as best I can so here it goes: You can always contest a traffic ticket. If the officer does not appear on the date of the trial then the judge will dismiss the case against you and no fine is imposed.The problem is that if you contest the ticket yourself, the court will require you to pay the fine up front and refund it to you if you win the trial. If you hire an attorney, you do not have to pay the court until the results of your trial (if you lose). The Vista court generally sets the trial date for about two months after the arraignment (first hearing).
As for your facts, to be honest, they sound like violations. You stated that you were going 89 which is a violation no matter what highway you are on. The fact that you were doing it to change lanes safely will be a bad argument with the judge, especially the judges who do traffic court in Vista. The carpool lane violation they may be more lenient with you, but if you crossed the double yellow to get in the lane, and the officer is there to testify to it, then the judge will likely find you guilty.
It will not hurt to contest the citation and set it for trial. You never know what may happen--the officer may not show up, may forget his notes, or forget to say some requirements during the trial.
I would be happy to speak with you about this ticket in more detail if you would like.
I agree with my colleagues. This is a ticket you want to fight with an attorney. An attorney might be able to get one charge dismissed and the speeding ticket reduced so that you can take traffic school.
With any luck if Officer does not show case will be dismissed.