I know that for each tier of the wedding cake, you should have a board that is 1 inch smaller under it in order for it not to show. What my problem is, how do you handle it if there is nothing to hold on to? Also, if I have piped decorations at the base, won't it be easy for them to break off when handling and stacking the cake? Even if I might use a tool like a spatula, I am still going to touch the piping. Another question also is, if the board is 1 inch smaller, the edge of the cake on top will be exposed to the fondant covered cake underneath therefore oils from the cake will seep into the fondant. Has anyone ever had this problem?

First of all - I wouldn't pipe the bottom design (around the base of tiers) sooner than after stacking the cake.

And as for the size of the board - if there is design around the bottom - beads and similar, I would take the exact same size board as the cake is. The design will cover the edges of the board. Use the smaller board only when there is nothing to cover it - these seemingly easy designs I like to look at but hate to make because there is nothing to cover mistakes.

I never heard the part about the cardboard is suppose to be smaller than the cake. My boards are the same size, or preferably, about 1/4" larger. I use this extra quarter inch as the icing guide, laying the bench scraper on the edge of this board when I do the smoothing.

As mentioned above, pipe the bottom borders on after the cake is assembled.