Thank you for your patience. Your answer is below. When you see the option to rate, please do so with a positive rating of 4 or 5 stars. You must do this in order for me to get credit. You can always continue to ask related questions even after you've given a rating. If you need more questions about the ratings, please feel free to ask.
ANSWER: As far as the DWIs from that long ago, this should not be a problem. They can look all the way back to then, but it is unlikely that they will look so far back.
As far as the tax returns, if USCIS discovers that an applicant owes back taxes, his application for citizenship will likely be denied. But tax issues are not an automatic bar to naturalization. If he can show that he's making an effort to resolve his tax issues or can show that he has paid the back taxes, he likely still eligible for naturalization.
Ultimately, the USCIS has discretion when making this decision, but I do not think these will be an issue at this point.
I hope that answers your question. To finish, I will need you to click the 5 stars (*****) at the top of your screen and hit the submit button. A BONUS is also appreciated if you feel I've earned one today. And remember, you can still ask follow-up questions if you need to.
If you want to talk on the phone, I am available to do that for an additional fee.
And if you have new questions in the future, you should write FOR JAMES in the question. That way, I become your personal immigration Expert.