FAQ for
Hannah Montana/Miley Cyrus: Best of Both Worlds Concert Tour (2008) More at IMDbPro »

Yes. When released on August 19, 2008, it became the first Blu-Ray Disc that can be viewed in 3-D. (A standard DVD edition was also available.)

It should be noted that the home video releases will be discontinued after a limited time.

Yes, she does. Near the end of "We Got the Party," one of the dancers takes Miley (as Hannah) off stage, and a body double comes out. This is to speed up the process of changing from Hannah to Miley. The double is Ashlee Ninon. A spokeswoman acknowledged this, but states that Miley otherwise sings live for the rest of the show.