This is my understanding of the system SBS intends to use. It is mostly abstracted from what they have said about titles, inheritance, and reputation.
In Elyria, titles have responsibilities and privileges attached to them. Each character will keep the responsibilities and privileges of the title they had before they married. They may be addressed by the equivalent title as their spouse, but they won't have the responsibilities and privileges attached to it. It would be more of an honorary title. Whoever has the title is also the one who chooses the heir, their spouse would only inherit the title if they were named the heir in the will.
To further complicate matters, however, those with titles can delegate some of their responsibilities and privileges, and I would imagine that a spouse would be the natural person to delegate to. So some might have greater authority granted to them by their spouse. This authority could be removed at any time unless their marriage contract specifies otherwise.
Someone married to a titled player will likely also have a boost to their reputation and greater social influence because they have such a close connection to someone prominent.
I don't know how taking each others names will work. I know I've seen in at least one fantasy series, whoever had lower status took the name of whoever had higher status. I think that would be a good system, but it will be up to the individual couples to decide.