Hippocampus,
To answer your question, yes it actually downloads the dive site each time. It never stores the data on your hard drive, but in fact only stores it in RAM. Most of the other features (3d models, images, etc..) are downloaded and stored on your hard drive as they don't consume much space and are shared across multiple sites (e.g. Sheepshead are on all of the California dive sites). A check is made to see if you have the most current model and if not, it is downloaded.
As for your suggestions and observations, thank you very much. Most of them are being worked on by our engineers or artists/designers. We will get the documentation page updated quickly.
Thanks again for your support, this feedback will help us make a tool that is better for the diving community.
Dive safe and eDive often!
Craig