questions were super basic and always seem to be for london, i'll post a review incl info in a minute
honestly only time they go beyond 'how'd you meet, who proposed' etc is if there's a criminal history or divorce, they may quiz you a little to confirm you know about the petitioner's history but this is for your safety, it's not an attempt to deny you.
I submitted DS-160 and booked interview when at ready status. They do seem to take awhile to send the letter, I think I was ready 26th Oct, letter sent 8th Nov and arrived 13th Nov. So if I'd booked an interview before 8th Nov, they prob would have cancelled it. Just always make sure you book 2weeks+ from ready date