Did you plead no contest at your arraignment? What is your reason for wanting to take it back now? While you are still within the time frame to do so, you have to have some reason other than "I didn't like the consequences." Talk with an attorney to see if this is even a possibility now - and next time, don't try to do this yourself.
Have you already been charged? Gone to court and had your arraignment yet? While I agree with the other posters about the nature and severity, with no record I would actually expect the DA's office to charge you with a misdemeanor (not withstanding the loss) based on my experience there. I agree that it is serious and can have serious consequences, so get an attorney ASAP. I was a Deputy DA in SMC for nearly 10 years - feel free to contact my office for a free consultation to discuss your...
I agree with the other posters. "High profile" doesn't necessarily mean good. There are many excellent attorneys who don't feel the need to get on TV every chance they get, and there are lots of excellent attorneys here on AVVO. Contact a number of them and go with whomever you like best, regardless of "profile."
First, were you subpoenad to appear? If so, then yes you have to show up. Yes, technically an officer could testify for you at the PH, but the DA probably wants to put you on the stand and have you testify. But before you go into court, talk with the DA and tell him/her what's on your mind.
You need to get an attorney to calender the matter and have it taken care of. There may be things that can be done, but only an experienced attorney is going to make any difference right now. There are many good ones here (myself included) who practice in Alameda county and would give you a free consultation to find out just what exactly the situation is.
There will be a hearing to determine whether or not the prior convictions the DA has charged as enhancements are "true." The DA will present certified copies of your son's convictions, and the court will determine whether your son sustained said convictions. Depending on what convictions he has and how they are charged, any number of enhanced penalties can be added onto your son's sentence. Only his attorney can tell you for sure what he's facing. Good luck.