I don't try too many Spectro, but I would guess that you might have to go with an ISO 400, F/2.8, and then the fastest shutter that will give you the shot without blurring from the movement of the parade itself. Most important is not to use the flash. It washes out the lights on the floats.
For fireworks, I like ISO 50 to 100, F/8.0, and around 1.5-3 second shutter. This does require a tripod. If you want to play a little, bring a black card to cover the lens, set it to a 16 second exposure and then cover the lens while the fireworks are absent from the sky then remove it when they are there. You can get about three to four cover/uncover cycles in the 16 seconds.