Will my friend's admission that she was driving and not me help me in my DUI case?

If you admitted to driving then you can be properly charged and convicted. If you did not admit to operating the vehicle and there were no witnesses to say you were there would be no probable cause to arrest you and insufficient evidence to convict you. I assume that you are asking if your friend is foolish enough to commit perjury and say she was driving will you be able to win the trial or have the case dismissed. The answer is that the prosecutor will figure out what is happening and she will be in a lot of trouble. She could be charged with perjury or break down on cross examination and admit you and she agreed to have her lie. If you ask her to lie it is Tampering with a Witness and Subornation of Perjury and you could be charged with those crimes. No lawyer is going to allow you to have your friend lie for you and risk being charged with Subornation of Perjury himself.

Yes if it is true. If it is not true, don't suborn perjury. If it is not true, however, you might still be able to win this DUI. Talk to a lawyer about the defense available-the officer has to observe the misdemeanor before he can arrest you on it.

Yes since you have to be drunk AND driving in order to be guilty.

Sounds like a valid defense. Hire an attorney to properly present your case in court.

It may or may not be enough to instill reasonable doubt in the mind of a judge or jury. More specifics are needed in order to give a more accurate answer to your inquiry. If you have been charged, contact an experienced DUI attorney in your area as soon as possible.

If you can get her to testify.