Apple TV, I'm so confused

[tawcat]

So, the wife is contemplating shutting off our U-Verse TV. We have a smart TV so I'm thinking as long as we have internet we'll be okay.

Looking at Apple TV, I'm not sure how it works. Will I need an Apple TV unit for each TV?

Also have a Bose Lifestyle Theater system, will I be able to run Apple TV thrugh the Bose?

She figures between Hulu Plus etc, she'll be able to watch the majority of her programs. Our main TV is a Vizio smart TV, the other is HD Toshiba.

Any suggestions/input/feedback is greatly appreciated.