What is a person's rights on criminal record privacy?

A year ago, I received an internship for an Accounting firm as an "Admin Intern" doing small tasks around the office. But just recently I was promoted to "Tax Intern" and I will be preparing returns so they told me that I need a PTIN. *When I was first initially hired, they NEVER asked if I had ever been convicted of a felony or required me to disclose this information on any hiring applications. They never asked, so I've never told them to hopefully avoid any negative judgments. But in 2008, I was convicted of a DUI. I paid all of my fines and completed every punishment that the court required me to perform successfully and on time. I have never filed my own personal tax return, so I am required to send in the W-12 form. Since I am required to have a PTIN, I have 2 questions: 1) What are typical felony convictions that the IRS are normally worried about and/or usually denied quite often? Will the IRS deny my request for a PTIN due to a non-violent DUI Conviction that happened almost 6 years ago? 2) Upon successful completion of my PTIN, will information about my felony conviction be sent to my employer or at least readily available to them? For example: will the IRS send my employer a copy of my W-12 whenever they are finished processing my application or is this particular information regarding my Criminal record strictly between the IRS and myself? *Yes, I know that this information is available through public records and can be viewed by anyone. I know my employer will not take the time to search for my records, but if this information is easily visible to him upon completion of application, then of course he will read it. I am just worried that if I apply and the IRS denies my application due to my prior felony conviction, that my employer would also fire me because (1) I failed to receive my PTIN and/or (2) I have a DUI conviction... Even if he doesn't fire me, I would like to keep this information as private as possible.