We were told by our lawyer to expect to be able to name each other’s parents and birth days, how many windows there were in our house, names of each others siblings, what side of the bed we sleep in, etc.  You can search the web for lists of possible questions.  Basically any question a couple living as a spouses would be expected to know.  

We weren’t asked any of the above.  

Our IO happened to have been  born in one of the countries we visited and asked us questions about his country to presumably test the veracity of our written evidence.  

We were interviewed together.  We had been together for over 4 years at the time of the interview, and we had a compelling case.

Shorter marriages are going to get more of the “newlywed game” (a game show form the 1970s).  Or marriages where the couple don’t live together.