Hi Kristy
After having all of my 6 children baptised into the Catholic Church, I am pleased to try and answer your questions.
My current parish priest says there are two ways you can have a Catholic Baptism. One is during the Mass and the actual baptism is incorporated into the service and the other is an after service baptism in which you turn up after mass and only have the baptism service. The only thing about the after mass baptism is the fact that the child at one point would have to presented to the congregation.
At 12 months of age, your daughter should have the capability of sitting in the church for the entire service, just make sure you provide her with snacks and little things to distract her. My children have been going to mass since they were little babes(I think 1 week was our youngest!)
My aunt currently sets up the church for all our baptisms and she makes sure that the water is always warm in the font (there is nothing worse than cold water being poured over a babies head!), and that the family feel comfortable in the church.
Sometimes, the priest may supply a candle or you might have to provide your own candle. The priest may also provide a white stole to be placed over the baby as a sign of innocence.

Hope that helps