The article is interesting, and they’re not really discussing the ramp.
The circumvallation wall is the main subject, and the fact that it could have been thrown up in a matter of a fortnight is impressive.
That many disciplined, motivated, and experienced troops - I wouldn’t bet against a body like that building a ramp in much shorter time frame.
Perhaps. The fortress on top could have well sustained a small group of people for a few years.
If Josephus got it “wrong” what other Primary Sources are available that disagree with him?
Usually, Historians go with the author who is closest to the event in time.
It’s a very impressive place.
I'm guessing that Roman Troops did little or none of the heavy lifting, that's what slaves were for.