General

How do I supply a full URL if the ContextPathBuilder prepends the context path?
The ContextPathBuilder does not support this for a good reason. A context is a dynamic entity which is bound to an arbitrary server. So you can't guarantee were your context is running in a distributed environment. If you still need the full URL, extend the ContextPathBuilder and override the getUserFilesPath method and return the full URL.
I want to pass additional parameters to the Connector. How can I achieve that?
The solution is a bit tricky but easy to do. This has beeen discussed here.

Localization

I have localized some messages but they don't appear in the alert boxes. Did I do something wrong? What can I do about it?
Unfortunately the JavaScript code which responds with error messages is incomplete. It does not cover all error numbers and has static error messages. You can fix this by searching for all files which read the GetResponse or UploadResponse and let the switch clause simply alert your localized message.