I have a very hard time getting my cake to stick to the cake board, I am using a very thin layer of buttercream, but my cakes end up sliding when they are being transported and it messes up the borders?  Any suggestions?

Use more buttercream and make sure you chill down the whole thing, to firm up the frosting.

Try melted chocolate chips or candy melts.  You could even use royal icing.

AI agree with Stitches : )

A dab of royal icing should hold it firmly in place.