POST-INTERVIEW UPDATE:
Alhamdulillah the interview went very well. The officer said she doesn't have any concerns and we should be getting our PPR in a week or two.
As for the interview, the officer was very nice and easy to talk to. A lot of what she asked was information we provided on the forms (how the relationship developed, how was the marriage arranged etc.). Dates of the wedding events and no of guests. After that she got into more specific details about how often we chat, what kinds of things we talked about in the beginning. She asked my wife (PA) some details about my life, then asked me to verify. What kinds of movies we watched, what games we played. Basically, stuff any husband and wife would know about each other. The important thing I think was just that our answers matched, more or less.
We also took a whole bunch of evidence. Wedding albums, hundreds of pics and hundreds of pages of whatsapp and skype chats, visit proofs etc. May have been overkill but we didn't want to leave anything to chance. She returned everything except the updated forms at the end.
So good luck to all the upcoming interviews. Don't stress out too much, it's easier than you think. Just make sure both of you know your story and what you submitted on the forms.