You can’t add RR to Spectral Binding, it’s a buff that gives positive things. Stuff like Veil of Shadows and Aura Censure can have RR because they give negative status, in this case to the enemy.
Spectral Wrath could have had RR skill mods but it can’t because it’s tied to Spectral Binding. If it was its own separate skill, not tied to anything it could have had more RR throughs mods.
Yeah, I’m guessing any extra fire RR would have to go on Ill Omen or something. Or maybe on Thermite Mines, so that we only have to cast one RR skill instead of two.
I don’t think anybody’s really against that side of things much, it’s mostly the Necro/Defiler stuff that’s getting us all talking. 
I’d probably want to use a 2x Blazeheart Defiler over a Pyro myself anyway (the idea of melee fire WPS appeals to me, as does the amount of potential tankiness between Blast Shield and the huge cooldown reduction on Mark of Torment), but it’s not like I hate the idea of it getting Occultist support. Seems like it would synergise pretty well, after all.
Spectral Wrath is it’s own skillfile. You can apply a skillmodifier to it very handily. (I think it’s called spectralbinding2.dbr, or whatever the internal name for spectral binding is.)
No, you can’t, i asked Zantai and he confirmed it. Spectral Wrath has to be its own separate skill, not tied to anything to be able to get skill mods. Or else it would have gotten fire RR mods to help fire Defiler because Veil of Shadow and Aura Censure have gotten RR mods.