When you open the Cinematic world and most of the others you’ll only find a few things or none at all seemingly, however, if you press ‘play’ you’ll see the worlds load in. This is due to the amount of memory that it would take (~24gb) to load all the streaming levels at once. You can open the GDC_Landscape_01 map, go to menu > windows > levels. At this point you should see a bunch of levels that are grayed out. You can right click on these and select “Load.” I woudln’t load them all at once or even all together, but just a few of them and you’ll see them pop in.
If you’re not familiar with the World Composition you can check that out in the documentation to see how this works a little bit better.
A lot of your questions can be answered in this forum thread and by the two linked YouTube videos. The developers sat down for two days of twitch streams for a couple of hours each and went through everything to help people understand some of the thought processes and how things work. It’s well worth the watch. The second video will deal more with the animation and matinee. The first video is discussing more the design of the Kite World and the tools that were designed to help create it.