....from cracking after it has crusted? I've noticed after I've completed my last wedding cake that the buttercream crusted so hard that it cracked in some places while delivery the cake. What causes this? Is there any way I can prevent this from happening?

Your board may not have been sturdy enough. Did it crack after you moved it?

cracked icing is probably 95% caused by insufficient board strength under the cake.

amen to what they^^^ said.

Besides using a stronger board (Use 2 or 3 glued together OR masonite OR a cake drum) you need to add just a bit more fat to your recipe. As little as a 1/4 cup can make a huge difference.