Thank you so much everyone for the insightful suggestions. And a special shout-out to Gail who pointed me to a very helpful visual in her blog and to Gorgeous thing's lace corset tutorial.
I will order a batch of spiral boning from Corset making, just need to measure the corset pieces. And I also finally bought the Susan Khalje cd-book Bridal Couture. I think it will be an intriguing addition to my sewing library, even tough this dress might be the only bridal gown I'll ever do. If I, hopefully, would get married to my boyfriend some day I'd definitely wear a more paired down look, as I don't really do full blown gowns - I am a little restrained that way! I would say that my own ideal wedding dress would be a classic 50's black chiffon illusion dress, like this one from Countess de Vintage.
Oh and the bride to be has finally scored some fabulous silk ribbon! The ribbon is very close to the original, just a little narrower, and will be perfect I think. I can't wait until she hands the ribbon over to me so that I can show you. But we did have a lace hiccup, the lace that she picked had almost run out in the store (just a meter left) and the other one that she liked had even less yardage left. So now we are perusing an English seller, Harrington fabric, and she has ordered three swatches from them.