Whether you can work as an EMT after a DUI conviction is a matter of policy of your employer (and maybe state regulation on EMTs), not a matter of criminal law. Talking with a lawyer before settling your case is good advice.
It will certainly reduce your chances of employment as an EMT. For liability reasons, it is highly doubtful you will be permitted to drive an ambulance. In the end, it will be up to the discretion of each employer whether to employ you, assuming you are able to hold a license.
They say you get what you pay for, and this response is free, so take it for what it is worth. This is my opinion based on very limited information. My opinion should not be taken as legal advice. For true advice, we would require a confidential consultation where I would ask you questions and get your complete story. This is a public forum, so remember, nothing here is confidential. Nor am I your attorney. I do not know who you are and you have not hired me to provide any legal service. To do so would require us to meet and sign written retainer agreement. My responses are intended for general information only.
you will be able to work as an EMT however that is up to your prospective employer. It will not keep you from getting an EMT license. However your license to drive with a Class license that you need to drive the ambulance will be suspended for one year
Why do you sport a defeatist attitude and presume you'll be found guilty? Most DUIs are fightable - they just aren't fought, mainly because too many attorneys also think it is a lost cause too. Pretend the charge is a sliced carotid artery and start working, not quitting. There are many superb DUI lawyers who cover the Fullerton court [including me], so contact one of them and stop caving in. I have had at least two paramedic/firefighter DUIs of bad facts and BACs, which didn't look winnable to the so-called defense lawyers they had initially contacted, but they came to me and we fought and won, after considerable effort and time. You're in the business [or want to be] of saving lives, so save yourself first, because if you don't have the hormones to do that, then lack of license would be the least of your missing credentials!