Hi Otto, Boston Acoustics TVee and Polk IHT soundbars can be programed to your existing TV remote. Not only volume, but mute as well. Not sure about other soundbar models.
With both the above systems, you would go into the Samsung's menu and turn off internal speakers. But because you own a Samsung there is a catch. Whenever you press volume or mute on the remote, you will receive a "Not Available" message for about three seconds on screen. The commands should work fine, but you will have to put up with the error message.
Polk includes a credit card remote you can program for these commands, thus avoiding the error messages. Personally, the error message doesn't bother me. I generally set the volume once at the beginning of movies/TV shows and that's it. My soundbar is part of a bedroom setup, so using just one remote (Samsung) is a huge plus.
And yes, these models plug directly into your TV, and work seamlessly with all your sources.