They likely had at least one research assistant, proofreaders, etc. Maybe the author is attempting to distribute credit and lead the reader to infer there was just more than one person involved.
No. Many scientific papers are written in third person. "We" actually means "me or us the author(s) and you the reader who is following along and checking these details"
Or, yes. I worked as a research assistant gathering data for a professor at University who wrote 100s of papers in the area of graphics and computer vision.
