If the DreamWhip frosting gets glossy as it sits, won't the color from decorations bleed out?
The only thing that has bled on me was the dark green bc onto the white Royal Icing decorations. Which I understand this is common with Royal Icing and any buttercream, that Royal absorbs color. And it took about 3 days. But the colors I have never had bleed onto themselves with straight buttercream.
I think what makes the gloss is when it is in an airtight (or practically) cake dome, that is sealing in the moisture. It wont get glossy in a box or straight out at room temp loosely covered.
As far as heat, no frosting should be left out at 100 degrees or so-they will all melt or breakdown. Since the Dream Whip has some kind of agent in it that binds (I havent read the box to see if it is cornstarch or egg white or what it is), AND it is all shortening (which has a higher melting point than butter), you should be ok at comfortable room temperature and maybe briefly at warmer temps. I took a cake to work when it was about 95 degrees and it sat in the parked car (no a/c) in a garage for 2 hours and was ok. But I would be very hesitant to count on much more than that with any icing....
No refrigeration required.
As far as flowers, I havent even tried roses yet. The icing is pretty stiff, but Im not sure if it is quite as stiff as say Wilton's Class recipe tho. But close. If youve done roses before, you should be a better judge of the consistency than I am. My newbie judgment is it is somewhere more than medium but just slightly less than stiff. So I am guessing if you add a tad more powdered sugar it should work.