No. Most airliners CANNOT dump fuel. This capability is limited to long range wide bodies, like this 787. Neither the 737 nor the A320, which constitute the majority of commercial air traffic, can dump fuel. Fuel dumping is normally performed at an altitude where it should be able to evaporate before hitting the ground, and it takes a long time, maybe 15 minutes to get from full fuel to maximum landing weight. Using it would have made no difference to the outcome of the flight other than making a larger fire on the ground.
No. I said a larger fire, and I meant it. The fuel on the aircraft is not the only thing feeding the post-crash fire. Dousing the entire flight path with an accelerant would have resulted in many many buildings being on fire, instead of just a few of them.