Some of these responses are hilarious. You need backups! You need second shooters! Are they just out of touch, or maybe they didn't read your post?
Here's some tips for you:
You won't need the tripod. You can't do long exposures with people in them... they move.
Practice shooting in the chapel before the wedding.
As for positioning, ask the B&G where you should shoot from. Do they want you up on the alter to get some shots, or just from the front row? Ask them.
Overweight people look best shot from up high. Bring a ladder, or find some way to shoot down on her.