So you will need to learn with the fact that N900 does not come with USB host mode enabled, and it probably cannot be easily hacked to enable it.
You could host some of the data online and export this. Examples are Dropbox, GmailFS. Or you attach your 1 TB on your home network, build VPN, and use UPnP over 3G. Won't work for XViD or DVD. Then you have to make choices (the horror).
Why do you not want to buy a WiFi router? Without some kind of USB to ethernet convertor you cannot use your hypothetic N900-with-USB-host-mode on your ethernet-only network.
N900 camera is not good enough?
The BlueTooth to USB converter might be able to be powered by the N900 I don't know, interesting question.