[Hoster]

FWIW (and do not know whether your generation went back to Honda transmission or still ZF):
1. I would stick with OEM - and have a friend who actually develops tranny fluids / additives who said for auto transmissions = always OEM ("you don't change often and why even bother with non-OEM")
2. as others indicated previously, dealers will do one drain and fill; for our '14, I did 3 x 4 qrt "flush" (basically drain and fill 3 times over a course of 1-2 weeks) around 60-70k then just drain and fill every 30k or so
3. rear diff - always Honda OEM due to SH AWD
4. front diff / TC - just M1 75W90 for years (my manual says 75W85 I think)