It sounds like you have a pretty good grasp of things. There are mandatory fines on a first offense DUI; a mandatory alcohol program and a license restriction. Now, however, Los Angeles (as a pilot project county) is requiring a mandatory ignition interlock devise for four months on a first offense. You can show up at your arraignment and handle it then - arraignment courts take guilty pleas all the time at the arraignment stage - and will give you only the minimum required. By saving money on an attorney, you can apply that toward your fines. So this is definitely worth hiring an attorney.
Only by hiring an attorney will he/she be able to asset your case. There are many facts that could possibly play in your favor.
As for when to get the best plea, it depends. If there are facts from the police report that play in your favor then a better deal may come after the arraignment.
Simply put, the District Attorney is an attorney with years of legal training and experience, as well as the judge. The only person who wont have any will be you.
Remember, that factors such as, whether or not the officer followed proper procedures, the calibration of the breath test machine, the probable cause to pull you over, all matter when handling a DUI case. The problem is, only a qualified attorney can assess what your case is worth.
A DUI charge may have many negative consequences from license suspension, rise in auto insurance, DUI classes, penalty assessments, fees and fines, etc.
Honestly, no one can tell you if you should hire an attorney but I can tell you that most if not all attorneys would hire an attorney to represent them if they ever got a DUI or any other criminal charge. Maybe that will help answer your question.
The one thing I notice that is a potential issue for the prosecutor is that there is no way the breath machine was accurate at the time of your arrest if you got readings of .13 and .16. If that occurred an error should have showed and you should have submitted a third breath sample. An attorney can be beneficial in a first time DUI but a lot depends upon the attorney that you hire. Some (you may have heard on the radio) are so called big name attorneys that handle DUI’s when in reality they will not be your attorney and have not practiced law in years. The key to hiring an attorney is make sure that will be the attorney for the entire case – including trial if it comes to that. For a first time DUI you need to negotiate with the DA a judge cannot do anything for you. LA DA’s will negotiate with attorneys but just understand no one can guarantee you anything.
I agree with with Mr. Driessen...the thing that stood out in the facts you presented is the very large disparity in the BAC levels. Usually the disparity is much lower - for example if you blew a .167 and .165.
Think of it this way, if you blew .07 roadside and .10 at the station, you would probably think that something was fishy and at the very least, you'd want more information about your case.
You can always get a public defender if you really cant afford a lawyer, but I would reccomend hiring someone who will be paid to put in the extra effort and time into your case if you have the money.
You should retain an attorney. Mr. Driessen is correct. While you appear to have a realistic approach to what to expect-only an attorney can fully advise you after reading the police report. I do see some issues with the tests that might come into play. Call if you have any questions.