Hi Sano,
The list of ideas you presented is pretty much a TODO list we have already, albeit not in that particular order.
But you should also know that Outerra is not a simulator, it's a world engine in a relatively early stage of development. It can be eventually used to make a simulator, even a complex one you've outlined, but it can be also used to make other types of games and applications in visualization and simulation areas. So we may not necessarily add all the features related to specific game using the engine in this stage of development. Making a complex simulator would be cool but it's also a very complex task and we are just a small team now. We will be adding stuff we need primarily for our first game, other features will come later as needed.
There was some preliminary support for buildings already, but we are now working on a more complex implementation that will enable us to render large cities effectively. I hope this will be soon contained in a blog update.
We will not be doing a walking pedestrians and animals rendering at the moment, this is a game specific thing - we are just making support for animated models. Other things you mention that are specific to games using the engine are the same case.
It will be also possible to make real airports, either by processing raster aerial images to a compatible format, or by using vector data to define it. But this also will come only later, when it will be used to make a simulator.
The release of the demo depends on one external thing we cannot directly affect, namely the ATI/AMD drivers. You see, we are using all the most recent features of graphics rendering API, and the AMD drivers currently have bugs that render the engine unusable, and we don't want to lose time on search for workarounds when the drivers will be eventually fixed and there's so much work elsewhere.
Apart from that, we also want to be sure the demo runs well, so we are also optimizing various parts of the engine and fixing various bugs.
Those 14GB is terrain dataset for the whole Earth. However, it's downloaded progressively via bittorrent/http protocol, and it works in such way that if you descended from space perpendicularly to a particular spot on Earth, it needs to download only some 15MB of data, if I remember it right. For a reasonably fast connection it means you can drop from the sky with the speed of a meteor and still fall seamlessly into the grass. Further data are automatically downloaded and cached as you are moving away. The demo may also contain some data from the start. For example, the data for
+z 3,2 region are somewhere around 300MB.