You need a good attorney to defend your dui. What I mean by that is that some dui attorneys will plead you out after making a few appearances. You don't need an attorney to take a plea. However it would be useful to have an attorney review your case, interview him about how defensible it is, and get professional counseling from him on the sanctions and consequences of a dui in your state. You could probably buy an hour of an attorney's time for a general consultation. After that it's up to you to decide whether you want to use him.
That is a very good question. Essentially, you have to ask yourself how important it is to you to have an OWI on your record for the rest of your life? Once you plead guilty, barring some unusual circumstances, it is very difficult to withdraw that plea and litigate the case. Unlike second and subsequent offenses, there is absolutely no risk to fighting your case. Because it is a civil forfeiture, you will not go to jail or be placed on probation. On second and subsequent offenses you may have more to risk by trying the case if the state reduces its offer based on a guilty plea. There are a host of other issues that are important to consider here but would require a much longer response. I am more than happy to talk with you on this issue if you would like to contact me.