I'm doing an all white cake with black accents. I want to try whipped icing instead of buttercream. My question is will it crust enough to ice smoothly and will it hold fondant flowers and a real ribbon if I tack it? I also want to do some black scrolls in buttercream. Will the base be too soft to pipe on? anyone have a favorite recipe? It's going to sit for several hours probably at room temp. so I need to know if it will melt?... I've never iced with anything but buttercream so I just don't know how well it works. Also most of the recipes I've found have butter will that make it yellow instead of bright white?...
Could you explain what you mean by "whipped icing"? Do you mean like a non-dairy "Rich's" "Bettercreme" type of icing?
What is the recipe for the icing you plan to use?
Like that others said, we need more info to help you.
If you are using real whipped cream it will probably break down if you don't stabilize it with gelatin first.
My favorite whipped icing recipe is the Whipped Cream Buttercream in the Most Saved Recipes section.
Most whipped cream recipes don't crust. They stay soft but you can still pipe on them. The WCBC recipe I use (also called Charlotte's WCBC) can have butter, shortening, or a combo of the two. I usually end up doing mostly butter but that is a taste thing. It holds up well unrefrigerated with mostly butter. It does have an off-white color. You can use half butter and half shortening if you want something lighter or more heat-stable.
As far as the heavy decos, I wouldn't do it. I have made white chocolate dots and put them on the side of the cake decorated with WCBC but I haven't done anything as heavy as fondant. I think if the flowers are relatively small it should be ok. You can use ribbon and tack it if you want, but you probably don't need to tack it.