1. I looked at messenger bags and other ways of stacking cubes but realised I would have to unpack all the cubes in order to access the ones I want. That might well work for others, but not for me. Both the rolling Zuca and the backpack Zuca allow identification of the cube I might want (although a tag on the sides of the cubes might be required) and allows me to remove just that cube whilst keeping the others in the case. The clear bags in the 'doors' of both kinds of Zuca and the side pockets also allow me to view and have access to a whole lot of small sundries and accessories which might otherwise be difficult to locate in a bag where the pouches and cubes were stacked up deep.

2. The Zuca pro is a frame with wheels with a detachable part made of the fabric and zippers. It's easy to wash and it is this insert that makes the Zuca frame into the Zuca case. The frame is strong enough to be a seat and there are accessories to allow you to make the seat more comfortable and less cold. Our Zuca pro came with an additional travel cover padded at the top which serves a similar purpose.

3. Can't help you with that question, the Zuca with four wheels is now called the Zuca Sport and is no good for air travel, its main market is ice skaters. The extra wheels are supposed to be good for getting the thing up and down stairs but make it inappropriate as cabin luggage. There at two different kinds of models that are FAA approved, the Zuca Pro and the Zuca Flyer, they are orientated in different ways so that you can pull out the accompanying cubes either length ways (the Zuca flyer) or width ways (The Zuca Pro, this is the one in the blog I linked to). Zuca Pro has an Artist version where the packing cubes are clear vinyl on top or there's the standard pro where the packing cubes are flimsier (and presumably lighter) and topped with mesh, but I don't have this version.