GMs don't perform weddings or change surnames like they did in EQ1. From what I have heard, in a future update, we will have the same ability to change surnames once per week like we did in EQ1. At this time, once you pick your surname, you're stuck with it. (Which is why, even if my character got married, she'd have no surname at this time
)
As for ceremonies, just get a friend or a roleplayer you know to perform it. My characters have always done it, being priests.