Re Marriage Laws: There is no such thing as common law husband and wife, i.e. if you live together as a couple that will not make you a married couple with the associated laws attributed to that in the eyes of the court. So, if you want the legal security, just don't get married or sign the marriage documents. You can have a ceremony if I remember correctly but the marriage can be voidable and therefore not a legal marriage ... but good luck convincing your prospective wife that you are not going to sign anything.
Source: Law grad, law has not changed afaik from the time I graduated.