I usually get about 50 cookies out of a batch, most that I do are approx. 3". I haven't used it on a cake only because I love the Satin Ice Fondant.
I'm going to try it this next week for the 40 cupcakes I need to do. I think they will turn out just fine.
As far as the rolled buttercream being greasy, I sometimes cut down the syrup a bit and blot with a clean white papertowel, that seems to help. Also-- keep your hands clean.