Firstly, thanks everybody for the replies
For the white I think I'll go with Ulthuan + Nuln Oil or Agrax Earthshade + White scar highlight. Looking around, I've also found that a base of Celestra Gray before the Ulthuan Grey could help. What do you think?
Regarding the bronze, wouldn't be the Balthazar Gold be too "warm"? I was thinking about Warplock Bronze base + Runelord Brass layer + Nuln Oil shade + final highlight of... well something

agree with the extreme highlight of silver though! Do you think it's best to layer them or could drybrushing also work?
Finally, I'm yet not completely shure about the purple glow. I will try Tiberius501's advice and see how I fair. Otherwise I'll ditch the idea and revert to the "classic green" glow