Asked to be backup photographer

A friend just asked me to be a backup photographer for her wedding (she's asked another friend to be the main photographer). I have never been a wedding photographer before and my photography experience is pretty limited, I was wondering if anyone can help me with the basic equipment I need to at least be some use. My current equipment are:

Nikon D700
Nikon 20-35mm f2.8
Nikon 50mm f1.4d
Nikon 85mm f1.8d
Nikon 28-70mm f2.8
Nikon 80-200mm f2.8
Tokina 100mm Macro f2.8
Nikon 28-200mm f3.5-5.6G
Nikon SB-700 flash
Hoya CPL filter

I don't have a tripod or any colour changing filters, do I need any of those, and which lenses should I take along with me, do I need anything else. Please remember I'm only the backup photographer (I guess if the main photographer gets too drunk I'll step in LOL)

The very fact that you need to ask tells me you should decline the offer!

As backup photographer you are there in case the main photographer doesn't turn up or his gear fails. Assuming the worst doesn't happen the other duties are to get more candid shots of the guests to complement the formal shots by the main photographer.

You have a pretty impressive set of kit there! I would use the 28-70 for indoors and outdoors. The 80-200 would be good for outdoor candids (indoor to if it is a large venue). The 50 and 85 will take a lot of beating for moving around grabbing "snaps" too.

Forget fancy filter effects - use post processing if you want that. And a tripod will just get in the way.