yes
No red Wind Devils but you can have red Blade Spirits. Not only I tested it in the past in-game but now I can quickly datamine this:
$ find . -iname "*winddevil*fx*"
./mods/gdx1/database/records/skills/playerclass06/pets/modifier_acidwinddevil_fxswap.dbr
./mods/gdx2/database/records/skills/playerclass06/pets/modifier_aetherwinddevil_fxswap.dbr
a) yes, on the first node of skills. But on the second and third nodes - damage and dots are not always converted. See the the link I posted in my first post to understand it.
b) simply if RR is needed, it’s added, for example this Acid WD conduit has also Acid RR added to Wind Devil. How did this get accepted? I guess it’s your fault that you weren’t there at the time to oppose this. Shame on you! You are years too late, should have come when Titan Quest was being developed which Grim Dawn inherits from 
Mechanics Betrayals Btw here are more reasons to rage for you (search forum if you don’t understand what some of them mean) and this is only some part of weird things in Grim Dawn mechanics. I didn’t even touch pets or melee that I know little of. But the game is balanced around these, there are compensations for imperfect mechanics (sometimes not satisfactory to some players)
c) yes