Can this set be used with Buttercream icing?

Yes but you need to lighty make the print. Your icing will stick to the stencil. I think I read somewhere on here that you can put a little bit of powder sugar on them and that helps but haven't tried that way yet.

yes I have used it several times and comes up well.

I wanted to attach a pic but it won't work If you have a look at my photos you will see a winnie the pooh cake that is buttercream with the press set... I have used it on fondant xmas cakes as well... Both work equally as well.