You should use a lower developer, but it’s not absolute. if you use a 25 just keep an eye on it as it’ll lift more. 

I would say no. This seems to be best for making very light yellow hair more silver-ish. 

Well, since your hair is white, you don’t need lift, so it would be a good idea to go with a low volume developer, like a 10, less damage that way. As for toner...I’d go with a something like maybe Wella Palest Beige Blonde or anything with the name lightest beige blonde in it. Wella Soft Blonde is pretty too.  My hair is naturally a level 5-6, but I’ve bleached it so the ends are now a level 8 champagne blonde & the roots are closer to a level 9 lightest golden blonde color. I use Wella Soft Blonde toner all over with 20 volume developer & “paint” Wella lightest beige blonde toner with 20 volume on the ends after I touch up my roots.  DO NOT leave the toner on your hair for the recommended time frame of 20-25, you’ll likely end up with a color result darker than you want. I usually only leave toner on to process 10-12 minutes MAXIMUM either after touching up my roots or when refreshing &/or killing brass on my ends. Leaving the toner in too long can result in a dark, grayish cast to the hair. It washes out after a few shampoos but that’s a headache because I only wash my hair every 2-3 days.  I’d advise you to snip our a small section of your hair, 10 hairs or so, (super glue or tie the ends together with white thread) and process that to watch the color change, timing it out & checking the results after 5 minutes then every 2 minutes. That way you won’t be surprised and you’ll have some control. I did this when going from dyeing my hair dark red for years to removing the color and bleaching it blonde. I don’t think the results would’ve been nearly as good if I hadn’t done an actual strand test. That way, no bad surprises.  I know your post was months ago, but none of the answers really seemed to address your question, so here I am! If you see this, I hope it helps! Post pics & a review once you’re done!!!

Wash it a few times with a regular shampoo...should pull some grey out and leave it more platinim.

I'd go for Golden Wheat or Champagne. The platinum is quite ash, lilac is pretty purple leaning toward grey, and Misty Rose is very pink.

The platinum toner combo they offer is great for getting out warm tones. If you wish to have warm tones do not use platinum. Champagne toner maybe to pinkish. Also ask about the number of developer to help even out your cool hair to warm tones. I would refer to a hair stylist for suggestions just in case.

It depends on what you are doing, if you're trying to lift a dark color to get to a lighter one 35 or 40. I am black American with dark brown hair and I dye my hair white. I always use a 35 toner to get my color to the blonde I need it to be. If you are using it with a toner it depends I use a 35 for everything. Any my hait has never "melted" out of my head. But you do run the fear of over processing it if its been bleached to much,

Yes you need the blonde brilliance 5 volume developer to go with the toner