Q: How many Audio & Video Tracks can you add to the Timeline in Vegas Movie Studio HD Platinum 11?
Answer: 10 x Audio Tracks and 10 x Video Tracks
In the newest version of Sony Vegas Movie Studio HD Platinum which is now called "Movie Studio Platinum 12", you can now add up to 20 x Video and 20 x Audio Tracks.
To add extra tracks to the timeline, simply right-click on top of a Video or Audio Track and select Insert Video/Audio Track.