how big typically is the pit at the concert?
From the map it looks like the entire main floor.
Although it depends on the venue, based on the shows I have been to on the the BS&B tour, I would say it's pretty big. I would guess it's average of 1/4 to 1/3 of the floor - although I was at one show where the entire floor was the pit! Another show I was at they enlarged the pit and moved the seating back.