Ok I have been asked to do a cake for an out of state party. If I make the cake with plain buttercream frosting can I freeze it, take it out and have it travel for 6 hours hours and then refreeze for a party 6 days later?

It's not the best thing for it, but will probably be OK. If it won't fit in a cooler, wrap the whole thing really well in a blanket to help insulate it. Dark colors may run when it condensates. If you make a hole in the icing down to the cake, it won't get as wet as it thaws. You can cover it with a decoration before the party.