No it doesn't show through. its a wee bit messy at the bottom, I have noticed but that be overcome using a fondant ribbon or fabric. but it does not show through - from my experience. I haven't done a cake for a wedding but have done tiered cakes. hth
http://www.youtube.com/watch?v=QgCu8-yrIxc try thisf site on utube. as for the ruffles never done it before. seems like straight long pieces which have been thinned out at the edge. i see a lot of this design cakes on CC. some one should be able to able to help you further.
Try using four pieces of wax paper underneath yr cake and covering yr board . once u have finished crumb coating, icing, etc pull the four pieces out and do yr border. when u place the wax paper, place it closer to the edge, but still underneath the cake