48, people do it all the time. Cunard's Queen Mary II, for example, spends several months going back and forth between New York and London. Few people take the ship round trip. They either sail to London, do some sightseeing, and fly home, or they fly to London or Europe for touring, and sail the QM2 home. There are folks sailing to New York from abroad, one way, on every cruise.
no, this is not true at all. What is only possible for US-flagged ships, however, is to operate cruises visiting US ports only without calling at a non-US port inbetween. As an example, a non US-flagged cruise ship must not operate a Hawaii cruise from - say - California that calls at Californian and Hawaiian ports only. This is due to the Passenger Services Act, an ancient (and rather ridiculous nowadays) law from the 19th century.
...the Author got alot of the facts wrong about the crew make up.
I am fairly certain he was using these figures as hypotheticals. It has no impact on his explanation of the details of the PSA itself, which is still valid despite the time that has elapsed since the article was published.