Why don't you tell your mom that instead of being tied to the kitchen all day, you need her support and help for the day in the things you need to accomplish before the ceremony?
It sounds to me like she just needs to be "needed." Does that make sense? So maybe see if you can schedule a hair appt with another stylist for her to have done while you are having yours done. You guys could talk while you are having your hair done together. Sort of a mom/daughter time before the wedding.
Just let her know that regardless of what she does or doesn't do, she is still needed. It is absolutely your day, but it is also her seeing one of her babies get married and I can imagine that would make her feel a little insecure about what her role is now. Despite the fact that you've been together with your husband for 10 yrs, the church wedding sounds like it is still a big deal for her, sort of a final word saying that she no longer has to take care of you.
As to having a restaurant dinner afterwards, I feel sure that any restaurant of considerable size could handle a crowd. However, of course, be sure to figure out where you want to go beforehand and call ahead to make reservations so that they are expecting your crowd. If you do this, it shouldn't be any problem at all.