Roy was a big drinker according to Murder Machine, when they did the autopsy on him he had the liver of a person much older (so the book quotes). Don't remember reading of him being into drugs.
I too do not recall ever hearing that De Meo used drugs, in fact I think he saw drugs as a weakness, although he had no objection for selling them. I don't think Murder Machine went into too much detail about drug use in the crew. We know that the twins and Henry B. did use but not as much as Dominic Montiglio. Roy was pretty upset about killing Chris, but he "Had his orders".
