Q1) Why is Part-Time and Full-Time occupants split? It gets calculated to FTE anyway.
Q2) If students are spending more than 8 hrs in the building, it would result in a larger than "number of students" FTE, but that's not how it's calculated. The student category only looks at the number of students.
Q3) I understand "transients" as the deviation from the daily FTE number. Is this correct?

In short, I have a detailed half hourly input for numerous occupant groups, with well grounded uneven male female ratios and I've graphed building occupation so I can see exactly where and what the peak occupation is, also for each occupancy group. That is how I came to the "transient" understanding stated above. It's the only way to make the template work to match peak occupancy.