Wedding Photography Questions

[ShannonKG]

Okay let me preface this by saying it is a favour for a friend. I will not be getting paid, and they have a professional photographer hired as well. The actual photographer was my teacher and I'll be a 2nd for her.

Okay so I'm taking some pictures at my friend's wedding Oct 1. I'll be 2nd, mostly shooting from the back of the church.

For equipment I have:
Canon Rebel
18-55mm
75-300mm lens

Equipment I'll be getting:
a couple 4g memory cards
a flash (? Not sure if we're allowed to use a flash or if it will be useful from the back of the church?)
tripod

So my questions are:
1) What are some tips you have for me? Some good sites to check out for info?
2) What other equipment should I have?
3) Should I be shooting in manual mode or is that too risky? Should I try to shoot in AP instead?
4) Anything else you can think of?

Thanks

[ShannonKG]

Okay I'm pretty sure I posted this in the wrong spot, but I'm not sure how to delete it :/ Sorry all.