I just bought my first 28# bucket of buttercream icing from Sam's Club. I have a wedding cake to make in a few weeks. I would like to try the icing before I put it on the wedding cake, for a trial run. If I open the bucket, does it need to be refrigerated? I plan to have a 16", 14" and 8" two layer, decorated (borders, etc) Is one bucket large enough?
I haven't decorated cakes in a while, so am not familiar with the new things going on out there in the cake world. Any help would be greatly appreciated.

Nope. No refrigeration needed.

I use the same icing and never refrigerate it. Just make sure that the lid is snapped on completely. You have more than enough icing to decorate the cake. You should have icing left over. It just depends on how elborate you get with the decorations and the borders. You should be fine. HTH.