Answer by jonas-echterhoff

To download your XML files, just use

var www : WWW = new WWW (url);

// Wait for download to complete
yield www;

and then use www.data or www.bytes, to access the data, which you can then process as XML (for example using the .NET Xml classes).

Uploading data (if you want to use http) works the same way, there's a version of the WWW constructor which takes data to upload as a second parameter:

WWW (url : string, postData : byte[]) : WWW