Apple TV has a refurb model on Best Buy for $79.99. Says it can push 1080p. Does this offer the new UI like the ATV 3 will have? I'm tempted to go with this because it features a HDD compared to the other two devices. Thoughts?
If I load files onto the Apple TV 1 (because it has a hard drive), can those be streamed to anywhere else? Such as an iPhone, iPad, Apple TV 3 given they are on the same WiFi network. Or do the files stay "locked" into the Apple TV 1 only?
Orange, no, TV1's hard drive is no kind of centralized hub for streaming out to other things. Think of it as solely a big(?) amount of space to locally store some media. The benefit is 1) being able to play media with the computer turned off/unavailable and 2) you can load it up with a lot of media and take it with you to someone else's house (or on vacation) and watch there.
Personally, I think those are great benefits and wish that Apple would normalize the TV3+ USB port so that those of us interested in local storage could hook up a hard drive(s) size of our own choosing and bring this benefit to the newer generations of this little box. But I wouldn't bet on Apple doing that.
There has also been a long-term wish for some kind of centralized iTunes media hub solution from Apple, including many wanting it to be done in an TV-type device (or in AEBS or Time Capsule-like devices). Unfortunately, that wish remains a wish (and IMO, a very good one). Maybe Apple will decide to make that one happen someday (but it will definitely not be within an TV1 which is pretty much abandoned tech beyond still working with iTunes).
The relationship between iDevices and TV1 is pretty much solely about using the iDevices as a nice remote (if you want to do that). No airplay, etc. TV1 is very much "an iPod (classic) for your TV".