The District Attorney represents the state, and everyone assigned to the District Attorney's Staff is in the prosecutorial role. The Assistant District Attorneys and staff personnel can discuss the process of how your case will be prosecuted through the court system, but they may not provide specific advice regarding how you should proceed.
If you are representing yourself in a civil or criminal matter, the ADA may discuss the facts of the case with you, but you need to remember that his or her role is adversarial to your interests. They can, however, give you an idea of the sentence recommendation, which they plan to request in the event you are found guilty.
If, however, you have retained legal counsel, either at your own expense or a court-appointed attorney, all communications must go through your attorney. This practice is required to protect your constitutional right to counsel and from self-incrimination.