For the photos you want, there is nothing that a digital camera can do that a film camera can't.
Because Spectromagic is made up of light bulbs, any camera with autoexposure should work well provided most of the frame is filled with the float. Definitely don't us flash - it's the lights you want to photograph.
Fireworks are more of a problem. Again, flash is useless. You need a camera that can be set manually with autofocus and autoexposure turned off. Your best bet is to invest in a tripod and cable release. set camera Set focus manually to infinity, turn off autoexposure, use a fast film and keep the shutter open for the full burst of the firework. If possible take several shots with different apertures to ensure at least one comes out well.
You should spend a couple of $$ on a photography book - they will have reccomended exposure settings.
BTW, I have gotten very good results with my camcorder by switching off autoexposure, then adjusting exposure manually until I get a good image on the LCD.
Andrew