<If they saw fire coming from that plane the tail coming off didn't cause that. There is nothing back there to burn unless you figured out how to light skydrol.>
1. Actually identifying the seat of a fire on an aeroplane from a distance is very difficult
2. Has anybody said at anytime pre-impact there was a fire in the tail?
3. The fin coming off definitely could have caused the fire. The violent yawing would detach the engines with great damage to the infrastructure and fuel pouring out in great quantities- possibly even from the wing fuel tanks above the engine.
4. I think in this case speculation is best avoided- the professional investigators will make a better job than us!