Are the voice and background tracks merged together when filming hollwood movies?

When we watch a movie we can hear background music and voices of actors. We also hear sound effects. When we watch a DVD movie the voice and background music merged inside a language track such as English language audio track. Audacity is program used to mix voice-overs and music. It is hard to create an audio track in another language if there is not a separate sound track. It is easy to dub a movie when there is a sound track.

1. When creating Hollywood movies, are there separate vocal track and a music track?
2. Is there a separate track for sound effects?
3. How do you mix voice and music tracks and convert it into a language track?
4. What is the software used to mix the tracks in question 3?
5. What is an original sound track (OST)?
6. Is the original sound track (OST) used when dubbing a movie?

Thanks in advance.