Download system (Server with Vaadin and external webhosting page)

Hey guys,

I have some general questions for a project… a download / file-mirror system
I have a server and a webhosting, server runs Jetty with Vaadin, webhosting is apache2 with some mods…
The server is for controlling, my webhosting should hold all files of the mirror
Server access : root (everything)
webhosting access: ssh-user, ftp, webdav, etc…

I want to provide the following:
A domain for hosting files, with user system

The complete frontend should be Vaadin
I want to grab every minute the filesystem (ftp or so), hold it in RAM and display it on frontend (with filters etc…)

Main problem for me: download system

How shall I use the webhosting in combination with the server…
Plain header redirect toi these files is not a good solution
I do not want the traffic go over the server either, it should be a direct download from the webhosting (if possible!)
Also a tracking system would be very cool (completed, aborted, resumed, etc…, same problem with plain redirect)

So far…
Hope nothing missed!

Thank you