God you guys certainly know how to put a damper on things 
I never thought about things like makeup, hair dresser and so. I thought about change of clothing. The last wedding I attended needed two changes one for day one for night -, I was 15 was part of a church choir, sang Ave Marie solo, how times change.
Going to a cousin's wedding this July with a guest list of 400 people.
OK dumb question, why should I be bothered about pics being taken, if his family find out why should I care?
How much would you charge
Oh boy no not at all!
But yes it's a social event. It requires preparation. Plus for you it's a "job" so you are on duty. That means your client (at least a genuine one) expects a certain standard of services both in the way you act and the way you look.
When you are a PA and travel with your boss it's similar. When you are a flight attendant, the same. You prepare what your job/function requires.
I would charge my standard rate for that number of hours. Each detail as to the outfit etc would have to be discussed, if it's a very fancy wedding then yes I would expect him to cover expenses. This is how you can quickly tell if the guy is a fantasist or not.
And yes it's is about YOUR FAMILY you need to worry, not his. If you and him happen to have an acquaintance in common people may ask questions when they spot you in a picture. So they can tell him your real name.
Basically it may be 12 hours of you being on permanent alert, in permanent paranoia of getting outed. If you want to risk it then at least GET A LOT of money out of it haha