This is documented here. He was a store keeper who lived in Jerusalem who passed away in 1954. More on him here.
He is notable for the singular accomplishment of reviewing ראש השנה and ביצה over 4000 times.
I don't know if this is relevant to the laws of gravestone inscriptions, but the mishna in Avos (5:25) says
בן ששים לזקנה
60 years to "old age" (זקנה)
I think it makes sense to reserve the designation of זקן\זקנה to people aged 60 and above, but one should consult a rabbi for practical advice.
To me, saying יום שבת קודש denotes a more religious meaning, whereas just saying יום שבת seems secular, because in modern Hebrew יום שבת simply means "Saturday." I'd go with יום שבת קודש.
Of course, this is one hundred percent opinion. Since this website is not intended for questions on Hebrew grammar, I assume you are looking for people's personal opinions ...
Rabbi Sorotzkin in Oznayim Latorah explains that there are two reasons why Rachel had a monument. The first is that since Yaakov changed the name of her son (Ben Oni to Binyamin) he put up the monument to show that it was not because of any lack in her. He also pointds out that she was buried "by the side of the road" and a monument was necessary so that the ...
The name of the deceased should certainly appear on the tombstone, but some Rishonim say that this was not always done.
The Gemorah says that there is no reason to make special monuments because “their teachings are their memorial" While monuments don't last, Torah teachings and actions are eternal, they are passed down from generation to generation and ...