For fireworks I like ISO 100, f11, manual focus out to infinity then dial it back slightly, remote on a tripod. Usually 2-3 sec exposure works. Try to get the fireworks early before the sky is filled with smoke.
For Fantasmic, I would recommend a fast zoom lens and lots of ISO. Because of the movement you will need to keep the shutter speed high. I shot it with my 70-200 f2.8 and while the focal length worked the limitation of 1600 ISO on my body did allow for fast enough shutter speeds and I ended up with some blurring. While some came out ok others were not acceptable. I'm hoping with my new high ISO camera body that the problem will be solved. We will see in 77 days!