Is the wall and ceiling winter white as well?

No - we used Benjamin Moore - Chantilly Lace Latex paint OC-65 in an eggshell finish.

What brand of grout did you use? We are attempting to recreate this bath (gorgeous work!) and can't tell from the photo whether the Snow White grout is a bright white or an off white. We are using Custom Building Products grout colors, and their Snow White is an off white. Thank you in advance, and for generously answering so many other questions!

The Snow White we used is more of a bright white - almost the same color as the tile. I hope that helps.

Thank you so much for the quick response!