Can I get US citizenship with a misdemeanor? How?

You appear to recognize that criminal arrest matters can have significant immigration-related consequences, including on the eligibility of a Lawful Permanent Resident to apply to become a naturalized citizen. This is true regardless of whether a criminal conviction becomes expunged - many people, including some attorneys who do not practice immigration law, mistakenly believe that an expungement will make an arrest and/or a conviction meaningless for immigration purposes, but they are wrong. In order to assess whether the petty theft and the DUI may stand in the way of eligibility there really is no alternative to engaging an immigration attorney to review copies of the disposition documents for those offenses (note that court-certified copies of those documents will have to be submitted to the USCIS in the naturalization application process) and advise you about eligibilities, options and strategies. Some immigration law firms, including mine, offer legal services on a "flat fee" basis so that a client will know the total expense from the very beginning, and a few immigration law firms, including mine, offer an initial consultation free of charge.