As to portions—and you might know this already—but wedding cake portions are calculated much smaller than “regular” cake portions. I guess it’s considered people will have recently eaten a meal and won’t be eating whacking huge slices as when serving, say, a birthday cake. So when you see the serving sizes, remember they are rather small. I think they’re approximately 1"W x 2"D x 2Layers Tall or, if one layer, then 2"x2"x1 layer deep.
That’s just from memory, though, so my figures might not be exactly right, but it’s far more pieces (and much smaller portions) than a 9x2-layer birthday cake serving about 12-15!!!!!