How does the orchestra work for the Tonys? Does the orchestra play all the songs from the shows that perform with one conductor for the night, or does each show bring in their own orchestra and conductor?
They have a gigantic orchestra. Unfortunately, unless you were Hugh Jackman singing at the Tonys for the Boy From Oz performance, you will be performing with a pre-recorded track - most likely the cast recording without the vocal tracks. There is one conductor for the group.
I believe that most of the Tony performances are done to backing tracks that are recorded shortly before the telecast by the Tony orchestra, often with a few guest musicians from the show's pit orchestra. Using cast recordings for this purpose would create a nightmare of reuse fee payments, and the Tony performances are frequently ridiculous medleys that have little to do with the structure of the cast album songs (or common sense).
"I have got to have some professional music!" - Big Edie