Does anyone have any advice on using gumpaste decorations, ( lace and pearl border with pearl dust) on a buttercream cake that will be refrigerated? I've read about fondant sweating and I'm not sure if I will have any problems attempting this. Should I attach the border with piping gel or royal icing? [/quote]

I would suggest royal icing. Piping gel doesn't get hard and isn't all that sticky. The trick I've heard of for refrigerating fondant with no problem is to put the finished cake in a box and wrap it in several layers of plastic wrap before you put the cake in the fridge. When you take the cake out. let it come to room temperature before unwrapping it. The idea is that the condensation forms on the outside of the plastic wrap, not on the cake itself. I will admit I've never tried this, but it stands to reason that it would work.