You are in the middle tier (High Rate of Alcohol) of DUI offenses in PA according to your BAC of .15. However, if you don't have a prior DUI or substantial criminal record, you may be eligible for an ARD program if the judge accepts your application. Contact a local attorney to better explain your rights and options going forward.
From the information you provided, it seems that you received a non-traffic citation and you checked the guilty box, and sent in the money and paid the costs. But, being that it was a summary-level offense, a not-fingerprintable offense, it would not appear in many criminal record repositories, such as the Pennsylvania State Police. It likely would appear in the public record. You may check your status on usjportal.pacourts.us to verify, but that link is not all-inclusive.
Call an attorney right away. This case has several defensible issues that a good defense attorney could argue on your behalf. You've taken a good first step in questioning the charges; now the next step is to have an attorney review the facts of the case in detail and make an informed decision on your behalf.
I agree with the other answers. An experienced attorney can review the ordinance to determine if the ordinance meets constitutional muster. This issue is highly controversial and has been challenged before. Contact an attorney with experience in municipal/zoning law as well as constitutional law.
First, you should hire an attorney to look into the facts of your case to determine if any immigration consequences could stem from the bench warrant. Then the attorney can guide you through the process of resolving the bench warrant in the most effective and efficient fashion.