I use the "notes" field on 1Password for just this sort of thing. Plus, I make them up, so if they ask me for my mother's maiden name, I would use something

I use the "notes" field on 1Password for just this sort of thing. Plus, I make them up, so if they ask me for my mother's maiden name, I would use something like "plexitrough", or my first pet is "Fortran". And I use different ones for different accounts. To answer your final question, using the true answers to the question is in fact insecure, and has been known to be so for nearly 10 years.