As for the challenged claim, that is a qualified yes (Michelle's staff was larger than Melania's, but not by that much, and there were reasons for it).
The Hill writes in an article dated October 2017:
Melania Trump has a smaller group of aides compared to her predecessor, Michelle Obama, according to the news outlet's analysis of White House personnel ...
This claim dates back to July 2018, and is based on a report from 1 July 2017, less than a month after Melania became the First Lady.
Snopes fact-checked it and explains that it is misleading:
Does Melania Trump have a smaller staff than Michelle Obama? Yes, but the disparity is smaller than alleged.
They explain that, comparing like-to-like, Melania ...
Obama is not the first sitting US president to publish an academic journal article.
In September 1897, William McKinley (25th) published an article in the American Annals of the Deaf.
The American Annals of the Deaf is
a professional journal dedicated to quality in education and related services for deaf or hard of hearing children and adults. First ...
By no reasonable standard did the Obama administration have a policy of separating minors.
To make sure we set the scene, the current (2019) Trump administration has a policy that when children and parents are apprehended together, the children are removed from their parents and incarcerated separately from them. The parents are offered no choice in this ...
No. The linked article in JAMA is a "Special Communications" and most academics would not describe this as a "academic journal article" reserving that distinction for articles falling under the category of "research".
There is no date on when the claim was for or when it was made, so it is impossible to know if the Obama percentage is correct at whatever time its author made them.
But based on the entire two terms of both presidents and according to Cleveland.com:
George W. Bush spent some part of 1,020 days away (35%), including 149 days at Camp David.
James Garfield published a short, apparently original, proof of the Pythagorean Theorem in the April 1, 1876 issue (see lower left) of the New-England Journal of Education. He was not elected President until 1880, though, and it’s more a note than a major paper. (Found from here.)
The journal itself appears to be a precursor to the Journal of ...