Very few photographers have what it takes to do formal wedding photography. The technical aspects of your craft have to be second nature, and you have to be able to manage people without offending them.
On the day of the wedding you, the photographer, will arrive at the bride's home about 2 hours prior to the ceremony. The purpose of this visit is not just the photography you will do.
This is your opportunity to develop a rapport with the bride, her family and the bridesmaids. In particular get to know the maid of honour, and enlist her help to organize the photos. This will set the tone for the remainder of the day, and she will be your best ally.
Getting to the church ahead of the bride is not just about getting your equipment ready. Introduce yourself to the ushers, and let them know what you are going to be doing. You will need a spot in the pews (on the bride's side if your flash is on the left of your camera) with a clear view of the aisle without guests blocking your shots. Have the ushers keep your sight lines clear when they are seating the guests.
The standard wisdom for making images of fireworks is keep your camera steady and use long exposures.
The f-stop number squared divided by the ISO speed should be about 0.6 (f8 at 100 ISO, f 16 at 400 ISO etc). Total exposure time is generally set to include some detail in the dimly lit foreground.