REMDK - thank you.

I'm not eligible for the STPC, would that have made a difference?

You mention QR J/F passengers and passengers that have booked Al Maha arrival service will have equal access to the same fast track facilities for immigration, so basically there are no reasons to book the Al Maha arrival service since I'm travelling in J on QR.
Does it make any difference that I need a visa (my nationality enables me to get VOA).

I think I will have my onward BP, but if not, would it then be beneficial to book the Al Maha departure service, or will I have same (or better) fast track privileges traveling as J passenger?

Namlakhorn