These decorations have been hand built from components. The castle is the smallest part of the Wilton sugar molds that were discontinued 15+ years ago. The bridge and steps built from cardboard, patterns may be on the Wilton website pattern locator section.
they might have most of what you are needing
I found this online,
This one is a 3 piece set consisting of carriage, castle and slipper:
Perhaps you could contact the seller and send a pic of the wedding cake to see if they know where you could find a stand similar to that one. If not you may have to use a multi tier stand that allows you to place them at varying heights and positions and fill in around the bases with tulle to resemble the "cloud" affect.