I need to make a cascade of edible orchids up the side of a three tiered cake.  I have never done this before. Since they are edible can I stick them directly into the cake or on the cake or do I need to wrap them prior to?  She doesn't want a wide cascade so it's not going to be that big. I also don't want them to wilt so if anyone can offer me advise on this I would much appreciate it. 

Also, she wants a single peony on top.  I know these are on the toxic list.  Since she only wants a single one I can't make a topper from it because she only wants one and does not want any greens.  Should I just put a layer of parchment paper in between the flower and the cake?

This is not a wedding cake but a birthday cake for a little girl.  Any advice would be much appreciated.