Wuala as Content Distribution Service ?

Hi. Again, this is not official but I'll answer based on what I know. All the files are spread in the P2P network since you upload the files with the client. You can password share any folder, and through the API you can get a direct http link to any file.

If you use: http://www.wuala.com/user/folder?key=XXX
people will be directed to a webpage where they can click to download the files contained in "folder".
If you want a direct http link you can use the contents API call: http://api.wuala.com/user/folder/file... This will automatically start the download of file.zip

When you download a file via http you are downloading directly from the servers, you don't get the additional boost from the P2P network so the download speed may be slower.
The Wuala team obviously prefer that people use the client rather than pure http because it helps them to save money on traffic.

Currently when you buy space or trade space you become a pro user and the main advantage is that you can turn off the ads inside the Wuala client. You don't get advantages on http but this may change.

Non official part but based on what I talked about with the team:
There MAY be speed restrictions in http access in the future, depending on the traffic generated by the service. There won't be those restrictions when using the client.