The only questions I can answer for sure is that media is always mounted read-only, so there's no way to delete anything, and only the Ultra and Streambar have a wired Ethernet connector. (not counting some Roku TVs).
I'm sure someone has tried a USB hub, but I have not.
Just reading here it seems that hard drives are hit or miss, but a 1TB drive shouldn't be a problem. The Ultra has been known to have issues with USB3 drives, but I believe the problem has been identified if not fixed quite yet.
Keep in mind that Rokus are very limited in codec support, so do some research first or you may find that many of your videos are not supported. There's no comparison between a WDTV Live device and a Roku. Roku pales in comparison for local streaming.
There's plenty of experts here, so this is probably the best place to ask questions. You can also dig through the Roku website.
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