I think that each tier is a two-layer cake approximately 4-5" tall that is covered in two different colors of fondant (or maybe BC). I do not think that these tiers are tall enough to require cakeboards and dowels within the tier - I think it is one cake divided into two colors.
I agree with ibmoser - it looks like it's just 4 tiers, 2 layers each tier, covered in white fondant with a blue fondant ribbon wrapped around the base of each tier with dots piped on the top and bottom of the ribbon. HTH!
I think the same thing. That's it's just a taller cake than normal, covered in fondant with a ribbon wrapped around it. Beautiful cake!