I just made icing using half butter and half shortening. This is the first time I have made this and am putting it on a cake for class. I love love the taste, so much creamier.

Will this crust like the 100% shortening? Can I use it under fondant. Does it have to go in the fridge. Can I use it to make buttercream flowers etc.

TIA

Yes to everything except the fridge. I've kept mine out as long as 2 days but it was still just as good as the first. Hey... it was our cake

As was said, yes to all your ?s. It can be left out for a couple of days but is best if frig'd. Because of the butter, it will start to melt (get soft) as you pipe with it - especially if you have warm/hot hands. You might want to thicken it for piping flowers - just add more powdered sugar.