Not originally is is not, no.
Yes
The fondant and marshmallow makes it smooth
If you want to make fondant at home, marshmallow fondant is much easier and simpler to make then traditional European fondant. All you need is 16 ozs of mini (mini!) marshmallows, two pounds of confectionery sugar, a sprinkle of water, and some shortening.
No. In fact, refrigeration will dry them out and make them rubbery even faster than leaving them in the cupboard.
I would say with icing unless you wanted to write on it with an eatable texter. Just ask a food craft store.
The main icings used would be Fondant and buttercream :) other accesories would be made of sugar and marshmallow and edible rice paper.
Knead more powdered sugar into the fondant until it's not sticky, but still pliable. Add a small amount of the powdered sugar at a time, so you don't use more than necessary, or the fondant will get dry and difficult to work with.
fondant that is rolled
Fondant is relatively easy to work with but, in my experience, not delicious at all. To make a 2 layer cake, you simply bake two different sizes. Drape the fondant over the bottom layer and trim, then place the smaller layer on top and cover it with fondant. If you do not plan to add additional decorations along the seam of the two layers (I would recommend doing so), you may want to cover the top layer with the fondant prior to placing it so you can wrap a little under and avoid scoring the bottom layer while trimming the top. If you are making a very dense cake, you may want to insert wooden supports into the bottom layer to support the top.
The fondant will crystallise
Can the fondant sealer be used instead of whipped fondant so it won't be very sweet or does the fondant have to rolled out thinner