My thoughts in order to your questions;

1, You have very good photography skills. Your skills are probably higher than many "wedding" photographers that are professional now. But there is more to it than the technical side. I think that as long as you are honest with her, and do not oversell yourself and then she decides to use you then it is ok. Be up front and honest just as you are here. If she is ok with it then, sure go for it because she has assumed the risk, most likely so she could save money.

2, Stick with your 7D and another if possible. Don't switch equipment at such an important time, it might backfire. Of course a 5D II works similar to a 7D, but what if some unknown pops up and you get a set of bad pictures.

3, One question after she decides to hire you, "Are you sure you understand that I have never photographed a wedding, and I want to make sure you are comfortable with this?"

Out of the many “I am going to be new a wedding photographer” posts I have seen on this site, I would say you are the one I would say go and do it.