Well, I can't answer all of your question. But when I went through in '82 I was a 63B (wheeled vehicle mechanic) and re-enlisted under the BEAR program.
I had to go down to Ft Gordon to get reclassed as an 05B before going through the Q course.
Several other folks were in the same position as I was.
It has changed through out the yrs, as others have commented, there is good free samples essay service
https://www.wowessays.com/free-samples/ but you had to be one of the MOS's they had on tms 05B radio operator, 31V (can't remember that duty descri), 91B Medic, 12B Engineer, 11B/11C Infantryman.
Once completing the Q course, we got our "S" identifier. 05BS3
Now I do remember some "soft skill" folks also, there were some 74 series guys from Sig Co 7th and 5th that went through and reclassed. But I think that only happened for a few classes though...