Hi, welcome. Nothing wrong with long posts, just use paragraphs so it’s easier to read.
Applying to be a driver can be a very long process with lots of waiting, don’t think it’s unusual, take some time to read some posts on here and you will soon see you are not alone.
Most courses are around 7-15 trainees, just depends.
I believe GA will be recruiting for the rest of the year or so I’ve heard, so replies may take a while.
The railway take on people from all walks of life, it’s just about what life experiences you can share in the interview (when the time comes) albeit some professions will be easier to give examples from (yours seems good for this).
Take one step at a time, don’t worry about any learning materials yet, as I said the process can be long and stressful and once you get chosen for assessments you will be sent some practice material by the TOC.
I wouldn’t worry about the BMI, I’ve seen some drivers that are 35+, as long as you can do basic mobility movements you are fine. (along with the rest of the medical)
Good luck on your journey.