O'Neil James 59 y Apr 21 1905 7829 Kings
If you know he's in Calvary, call 718-786-8000 and give full name and date of death. They will give you the location of the Section, Range, etc. By Section you will know which of the 4 Calvaries that James O'Neill is buried in.
Many people woud come here and not be able to find the work that they did in the original country, so they worked at what they could. If one thing did not work out, they became a carpenter or a saleman -- whatever gave them a paycheck.
If you cannot call, let me know. You may find that he's buried in Calvary but in another grave since they were estranged. She likely would not have changed her name, nor divorced. Possible, but unlikely.
At the time, Calvary was the Catholic Cemetery when St. Patrick's was already full and the NY law stated no cemeteries could be in Manhattan (New York county). So, the Archdiocese bought the area of Calvary 1 and it quickly filled -- resulting in them buying and creating 3 more Calvaries a bit further east in Queens County. I'd say it's still likely he's buried in Calvary 1, assuming that that James is your relative and he does seem the closestt.
Accuracy was not important. If he had no relative contacts when he died, neighbors and friends might be asked for length of time in the U.S. -- and 40 years was a good guess when friends did not know exact year, so they "guessed" knowing it was a long time just not how long ago. Engineer, he may have been one in Ireland or trained, but never could find enough work as an Engineer here.
A liquor dealer could be a liquor salesman -- they might not want to have mentioned liquor (already becoming controversial here in the first decade of 1900) and felt that "salesman" covered his profession without divulging what he sold.
I have found that people were suspicious of government - our own and their home country. I have one family where the father used 3 different years of birth to cover up 2 previous marriages -- and then a new first name for his third (but not final marriage) -- to cover up that the first two marriages were not marriages at all or without benefit of divorce. But it was him. And in early 1900s, this was easy to do because the enumerator or doctor did not bother to check things like exact time in country or did he spell his name O'Neil or Neil when he signed up for work or moved to a new lodging house? And there were no social security numbers. You'd be surprised at the inaccuracies that were intentional so the government could not really keep track and how easy it was.
Also, your relative may have entered through Canada, spent some time there, and then left for the U.S.
Unfortunately, you are dealing with a common name. I found no marriage between James O'Neil and either Angela or Hannah Ames in NYC.