On the storage space issue.
The download is 20 MB. When installed, the program's directory uses 27 MB.
The extra space requirement comes in as the program caches downloaded imagery. One tour I took caused about 30 MB of imagery to be downloaded.
So far I have downloaded about half a gig worth. Though you can purge this cached information, it is best to keep it as subsequent views of the same information load much faster.
The 10 GB number seems to be how much imagery the program will download if you view most everything available. Look for this number to grow.

Clearly, this is a resource for a broadband connection and seems like a good candidate to be offered on DVD or Blu-Ray disk for those lacking the bandwidth.
Kelly, I am playing around with doing a video capture of a short session. So far, I am having a hard time keeping the resulting movie file within reason for you to download.
I will try to keep it under 20 mb or so.

You can start the download at night and hope it is finished when you wake up.