+1 for Steve's comments
Denise, some of the comments so far I have a thought on;
1, A contract, in my state a proposal acts as the contract if an official agreement is not signed. Nothing wrong with writing up a proposal and describing your fees and all the other things you need to address with her.
2, She hired you because of your pictures on your site. Did you rent lighting for these? I bet not. I say be honest with her, describe what equipment you are bringing as backup. If she wants backup flashes or other equipment she would have to pay for it. You can explain your set up in a proposal.
3, You told her your abilities and that you would shoot the wedding, backup photographers cost money if she wants one. You could mention this to her, explaining that while you will try and get all the important shots you are only one person. If she wants backup it costs.
4, I think you will need a release to use the photos later for advertising.
5, Shoot this event with the resources you have. Go to the venue days in advance and test to see what your best lighting situation would be.