[Amanda]

I think the 14" would probably hang off the side of the cake. I'm not 100% sure about that, though. Just get out your pans and start playing around with stacking and configuring them. I think that's the best way to visualize what you are wanting to do.
As for boxes, I know that they sell them here...but I don't use them so I can't help you with pricing.
Good luck!