What about the hypothesis of two shooters - one in the second floor room with a window? For Crooks to get shots 1 - 3 off within just a few seconds of sweeping the police officer with his muzzle seems pretty quick.
Thinking a more professional sharpshooter got the first 3 off - then Crooks sprayed 4 - 8. 9 was suppressed and was the kill shot from the CST.
Good points ... the shot that hit the person near the aisle between the grandstand sections would line up better with probable paths if it came from one of the 2-story windows.