For what it's worth, Charity Navigator gives them 4 out of 4 stars with a 98.33/100 rating: https://www.charitynavigator.org/ein/200049703
Meanwhile eg the American Cancer Society gets 73/100 and spends more on fundraising than WMF's entire budget, so oncologists can snort blow off hookers in Vegas, but nobody cares.
By "full-time" you mean paid?
Researchers can't contribute to Wikipedia at all, unless the "research" consists of a literature review.
https://en.wikipedia.org/wiki/Wikipedia:No_original_research
And if there were full-time paid editors, I'd stop editing immediately, and instead contribute my efforts to the fork that would inevitably result.