I agree with Patrincia—do not put fondant on cheesecake. I have never done it, but I predict that you would end up with a mess. Cheesecake is very moist, and the part of the fondant that is touching the cheesecake would soak up that moisture and get sticky and gloppy. This is my theory, anyway—and it is a theory that I’d rather not test out on a wedding cake!
In my opinion, cheesecakes are already a perfect surface for decorating with ribbon and fresh flowers—there is no need to cover the whole thing with another layer of frosting, although Patrinica’s suggestion about White Chocolate Cream Cheese Buttercream is the one to go with. I have used it to pipe a border around the bases of my cheesecakes.
Regarding the color of the cake, we’ve discussed this before on this board, but it’s worth repeating: There are many shades of white. If you pick the right color ribbon and flowers, and the right cakestand and a colored tablecloth on which to display the cake, it will look white, not off-white. You might want to hold up swatches of color against some leftover cheesecake and see what looks best. Also, use the version of Rose’s recipe that calls for whole eggs as opposed to all egg yolks, and that will make the finished cake whiter. Good luck!