Will the music in version 1.0 be completely removed?
More than likely you will be able to hear it somewhere.
Will we see the return of dungeons and/or open areas without music? (Just ambiance.)
We basically set it up so that music is not playing all the time and in every location in ARR, so there will be dungeons and areas without music.
There are many occasions where we will play a bit of ominous music at the entrance, and then it will change to just ambient sounds. During battle the music will play, but this is a feature of Alpha and will most likely change in the future. There are of course times that content-type dungeons will have music playing the whole time.
Can you toggle the chocobo/goobbue music on and off?
In Alpha, after the riding music loops about 1 and a half times, it will no longer continue to play. We are planning to have a toggle option at launch as well!
Also, for mounts, though it will be after the launch, we are thinking of a variety of gimmicks, so look forward to it!