Do I need to mention that I had been to USA as a minor (with expired passport and visa details) on the DS 160? If yes, is it okay to appear for B2 visa not having the expired passport but only a printed proof of the visa? I have all the details of my old passport and visa with me but it is not in the country I am residing in currently. Will I face any issues in the visa interview?
You must answer the DS 160 questions accurately. The consular officers have access to electronic records of travel into and out of the USA as well as records of visa approvals and refusals. It's highly unlikely that you will even be asked to produce old passport(s). I have never been asked. And if asked, just tell the officer why you don't have it.