Try to keep ISO down as longer shutter-times tend to give you more grain - especially at night. If you're not to far away, leave the 80-200 at home, you won't need it. In all other aspects, you already said what's important. Tripod, cable-control and shutter-times depending on the intensity of the fire-works. 1-5 seconds is fine, perhaps start with 1-2 seconds and close the aperture as needed. Don't worry to much .. it's a lot easier as one would think ;-) Have fun! Tom