Because it has no legal value, a symbolic wedding ceremony offers you a lot of flexibility: It can take place pretty much anywhere. You can include everything you like, provided it is suitable and in-keeping with the official nature of a traditional wedding ceremony.
A symbolic or humanist wedding ceremony allows you to make a statement if you wish to stray from traditions or, on the contrary, keep some elements of traditions in a pleasant and relaxed atmosphere.
Usually the documents you need are:
Do I need to have a civil ceremony as well as the Catholic ceremony?
No. If you are having a Catholic marriage ceremony here in Spain then you do not need to have another legal ceremony either in your country or in Spain as the Catholic service also counts as the legal one. At the rehearsal your wedding co-ordinator will take your civil letters of Freedom and use these and your other documents to register your marriage civilly at the townhall the day after your church ceremony.