Hi everyone!  I am new to this forum and found it through Google search.  I see that there are a ton of knowledgeable people on this site.  

I am doing a cake for an order this weekend.  The customer has requested fondant decorations on a buttercream frosting.  

My plan is to use shortening in my frosting because that seems to crust much better than by using butter.  I need to stick circles to the sides of the cake and a few overlapping the edges.  

My questions:

Can I do this with fondant on buttercream?

Should I let my buttercream get a good crust on it before I apply the fondant decorations?

What do I used to stick them on there?  Dots of buttercream?  Water?  

Will I need to refrigerate this cake afterwards until it is picked up the next morning?

Thank you all!

Simplest way is to just use water.  Brush a tiny bit on the back of your fondant decorations and it will stick to your buttercream easily.  You can do it after your buttercream has crusted up and you do not need to refrigerate.  Good Luck!

Thank you so much!!!!  That helps a ton!  

I have also used piping gel and it works well

The simplest way to attach fondant decors to bc is simply to slap them on there BEFORE the bc crusts.  easy!